CORRELATION OF MICROVASCULAR COMPLICATIONS OF DIABETES MELLITUS WITH HbA1c AND SERUM MAGNESIUM

INTRODUCTION

Diabetes mellitus is a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion ,insulin action or both.The chronic hyperglycaemia of diabetes is associated with long term damage ,dysfunction and failure of various organs, especialy the eyes, kidneys,nerves, heart and blood vessels

EPIDEMIOLOGY- The worldwide prevalence of diabetes has risen dramatically over the past two decades,from an estimated 30 million cases in 1985 to 285 million in 2010.Based on current trends, the International Diabetes Federation projects that 438 million individuals will have diabetes by the year 2030.

India leads the world with largest number of diabetic subjects earning the dubious distinction of being termed the “diabetes capital of the world”. According to the Diabetes Atlas 2006 published by the International Diabetes Federation, the number of people with diabetes in India currently around 40.9 million is expected to rise to 69.9 million by 2025 unless urgent preventive steps are taken

HISTORY- Diabetes is one of the oldest known diseases. It was documented in the writings of Hindu scholars as long as in 1500 BC. They had already described “a mysterious disease causing thirst, enormous urine output, and wasting away of the body with flies and ants attracted to the urine of people”. The term diabetes was probably coined by Apollonius of Memphis around 250 BC, which literally meant “to go through” or “ siphon” as the disease drained more fluid than a person could consume. Later on, the Latin word “mellitus” was added because it made the urine sweet. The first description of diabetes was given by Arataeus of Cappadocia in Asia Minor in the second century AD. Aretaeus said-‘ the fluid does not remain in the body, but uses the man’s body as a channel whereby to leave it’. His graphic account of the disease highlighted the incessant flow of urine, unquenchable thirst, the ‘melting down of the flesh and limbs into urine’, and short survival.

The Hindu physicians, Charaka and Sushrutha, wrote between 400 and 500 BC were probably the first to recognize the sweetness of diabetic urine. Indeed, the diagnosis was made by tasting the urine or noting that ants congregated round it. Charaka and Sushrutha noted that the disease was most prevalent in those who were indolent, overweight and gluttonous who indulged in sweet and fatty foods.

In 1869, Paul Langerhans discovered ‘islands’ of cells scattered through the gland’s parenchyma of pancreas.

In 1921, insulin was discovered at the University of Toronto by Frederick Banting, Charles Best, and J.J.R. Macleod in acid-ethanol extract of pancreas. The name insulin was coined by Macleod.

In 1922, an extract of pancreas made by Banting and Best was injected into Leonard Thompson, a 14 year old boy dying of diabetes in Toranto General Hospital. It failed to relieve him of his symptoms and caused a sterile abscess, hence the experiment was judged as failure. But later, an injection of a separate extract reduced Thompson’s blood sugar to normal and abolished his glycosuria and ketonuria. This confirmed the glucose lowering property of the hormone “insulin”.

In 1940, Auguste Loubatieres developed the first oral hypoglycemic agent the sulfonylureas suitable for clinical use.

In 1955, Frederick Sanger first time reported the amino acid sequence of insulin.

In 1976, the glycosylated hemoglobin (HbA1c) test was introduced as a monitor of glycemic control. In 1976, Koenig et al demonstrates a correlation between blood sugar and HbA1C

In 1976, Tattersal et al in their twin study observed that increased level of HbA1C in diabetics is a metabolic abnormality rather than a genetic marker

In 1978, production of first recombinant insulin was announced. In 1992, Husmann dozy observed an increased level of glycosylated haemoglobin in diabetics

In 2003, the names Insulin Dependent Diabetes Mellitus (IDDM) for Type 1 and Non-Insulin Dependent Diabetes Mellitus (NIDDM) for Type 2 were formally dropped.

CLASSIFICATION OF DIABETES MELLITUS – Diabetes mellitus is classified on the basis of pathogenic process that leads to hyperglycaemia as opposed to earlier criteria such as age of onset or type of therapy

ETIOLOGIC CLASSIFICATION OF DIABETES MELLITUS: I. Type 1 diabetes (β-cell destruction, usually leading to absolute insulin deficiency) A. Immune-mediated B. Idiopathic II. Type 2 diabetes (may range from predominantly insulin resistance with relative insulin deficiency to a predominantly insulin secretory defect with insulin resistance) III. Other specific types of diabetes A. Genetic defects of β-cell function characterized by mutations in: 1. Hepatocyte nuclear transcription factor (HNF) 4α(MODY 1) 2. Glucokinase (MODY 2) 3. HNF-1α(MODY 3) 4. Insulin promoter factor-1 (IPF-1; MODY 4) 5. HNF-1β(MODY5) 6. Neuro D1 (MODY6) 7. Mitochondrial DNA 8. Subunits of ATP - sensitive potassium channel 9. Proinsulin or insulin conversion

B. Genetic defects in insulin action

1. Type A insulin resistance 2. Leprechaunism 3. Rabson-Mendenhall syndrome. 4. Lipodystrophy syndromes.

C. Diseases of the exocrine pancreas-pancreatitis, pancreatectomy neoplasia, cystic fibrosis, hemochromatosis, fibrocalculous pancreatopathy, mutations in carboxyl ester lipase.

D. Endocrinopathies – acromegaly, cushing’s syndrome, glucagonoma. pheochromocytoma, hyperthyroidism, somatostatinoma, aldosteronoma.

E. Drug or chemical-induced - Vacor, pentamidine, nicotinic acid, glucocorticoids, thyroid hormone, diazoxide, β-adrenergic agonists, thiazides, phenytoin, α-interferon, protease inhibitors, clozapine, beta blockers.

F. Infections - congenital rubella, cytomegalovirus, coxsackie

G. Uncommon forms of immune-mediated diabetes - “stiff-man” syndrome, anti-insulin receptor antibodies.

H. Other genetic syndromes sometimes associated with diabetes -Down’s syndrome, Klinefelter’s syndrome, Turner’s syndrome, Wolfram’s syndrome, Friedreich’s ataxia, Huntington’s chorea, Laurence-Moon-Biedl syndrome, Myotonic dystrophy, Porphyria, Prader-Willi syndrome.

IV. Gestational diabetes mellitus (GDM).

Not e: MODY-Maturity onset of diabetes of the young

The two broad categories of diabetes mellitus are designated type 1 and type 2.Type 1 results from autoimmune beta cell destruction,which usually leads to insulin deficiency.Type 2 is a heterogenous group of disorders usually characterized by variable degrees of insulin resistance, impaired insulin secretion and increased glucose production.Distinct genetic and metabolic defects in insulin action and/or secretion give rise to the common phenotype of hyperglycaemia in type 2 DM

Type 1 diabetes mellitus-

(β-cell destruction usually leading to absolute insulin deficiency)-This form of diabetes which accounts for only 5-10% of those with diabetes, results from a cellular mediated autoimmune destruction of the β-cells of pancreas. Markers of immune destruction of the β cells include islet cell autoantibodies, autoantibodies to insulin, autoantibodies to glutamic acid decarboxylase(GAD65) and autoantibodies to the tyrosine,phosphatases IA-2 and IA-2B.One and usually more of these autoantibodies are present in 85-90% of individuals when fasting hyperglycaemia is initially recognized.Also the disease has strong HLA associations with linkage to the DQA and DQB genes.In this form of diabetes ,the rate of β-cell destruction is quite

variable,being rapid in some individuals(mainly infants and children) and slow in others (mainly adults).This is usually associated with other autoimmune disorders such as graves disease, hashimotos thyroiditis,addisons disease, vitilligo,celiac sprue,autoimmune hepatitis,myasthenia gravis and pernicious anaemia

Type 2 diabetes mellitus-

This form of diabetes ,which accounts for 90-95% of those with diabetes,previously referred to as non insulin dependant diabetes or adult onset diabetes,encompasses individuals who have insulin resistance and usually have relative (rather than absolute)insulin deficiency.The risk of developing this form of diabetes increases with age,obesity and lack of physical activity.It occurs more frequently in women with prior gestational diabetes mellitus and in individuals with hypertension or dyslipidemia and its frequency varies in different racial/ethnic subgroups.It is often associated with a strong genetic predisposition, more so than is the autoimmune form of type 1 diabetes. However the genetics of this form of diabetes are complex and not clearly defined.The symptoms of marked hyperglycaemia include polyuria, polydipsia,weight loss and sometimes even polyphagia and blurred vision.Impairment of growth and susceptibility to certain infections may also accompany chronic hyperglycemia.Acute life threatening consequences of uncontrolled diabetes are hyperglcaemia and ketoacidosis or the non ketotic hyperosmolar syndrome.Long term complications of diabetes include retinopathy with potential vision loss; peripheral neuropathy with risk of foot ulcers,amputations and charcots joints;and autonomic neuropathy causing gastrointestinal,genitourinary and cardiovascular symptoms and sexual dysfunction.Patients with diabetes have an increased incidence of atherosclerotic,cardiovascular,peripheral arterial and cerebrovascular disease

SPECTRUM OF GLUCOSE HOMEOSTASIS AND DIABETES-

Impaired glucose tolerance patients-have impaired fasting glucose and are now known as prediabetics –they are risk factors for future diabetes as well as complications

Therefore categories of FPG values are as follows:

FPG<100mg/dl(5.6mmol/l)=Normal fasting glucose FPG 100-125mg/dl(5.6-6.9 mmol/l)=IFG(Impaired fasting glucose) FPG≥126mg/dl(7.00mmol/l)=Diabetes

Corresponding categories when OGTT is used 2h post load glucose <140mg/dl(7.8mmol/l)=Normal glucose tolerance 2h post load glucose 140-199mg/dl(7.8-11.1mmol/l)=IGT(Impaired glucose tolerance) 2h post load glucose ≥200mg/dl(11.1mmol/l)=Diabetics

Risk factors for type 2 diabetes mellitus-

Family history of diabetes (i.e. parent or sibling with type 2 diabetes) Obesity (BMI >25 kg/m2) Physical inactivity Race/ethnicity (e.g., African American, Hispanic American, Native American,

Asian American, Pacific Islander) Previously identified IFG or IGT or an HbA1c of 5.7-6.4

History of GDM or delivery of baby ≥ 4 kg ( ≥ 9 lb) Hypertension (blood pressure >140/90 mm Hg) HDL cholesterol level ≤35 mg/dL and / or a triglyceride level ≥250 mg/dL Polycystic ovary syndrome or acanthosis nigricans History of vascular disease.

DIAGNOSTIC CRITERIA FOR DIABETES MELLITUS An international expert committee, after an extensive review of both established and emerging epidemiological evidence, recommended the use of the glycosylated hemoglobin (HbA1c) levels to diagnose diabetes, with a threshold of ≥ 6.5% and American Diabetes Association (ADA) affirms this decision in 2010, and it is being gradually accepted for the same worldwide.

ADA 2012 Criteria for diagnosis of diabetes mellitus 1. HbA1C ≥ 6.5%. The test should be performed in a laboratory using a method that is

NGSP certified and standardized to the DCCT assay.

OR 2. FPG ≥ 126 mg/dl (7.0 mmol/l). Fasting is defined as no calorie intake for atleast 8

hours.

OR 3. 2-hours plasma glucose ≥ 200 mg/dl (11.1 mmol/l) during an OGTT. The test should

be performed as described by the WHO, using a glucose load containing the equivalent of 75 gm anhydrous glucose dissolved in 200 mL of water.

OR 4. In a patient with classic symptoms of hyperglycemia or hyperglycemic crisis, a

random plasma glucose ≥ 200 mg/dl (11.1 mmol/l).

Note: In the absence of unequivocal hyperglycemia, criteria 1-3 should be confirmed by repeat testing.

COMPLICATIONS OF DIABETES MELLITUS

Diabetes causes both macrovascular and microvascular and other complications.

Macrovascular complications are manifested as,

Coronary artery disease Cerebrovascular disease Peripheral vascular disease

Microvascular complications are manifested as ,

Eye disease- retinopathy(non proliferative/proliferative),macular edema,cataracts,glaucoma,

Neuropathy-sensory and motor (mono and polyneuropathy) ,autonomic Nephropathy.

Other

Gastrointestinal(gastroparesis,diarrhoea) Genitourinary(uropathy/sexual dysfunction) Dermatologic

Microvascular complications are mainly because of hyperglycaemia,whereas insulin resistance is the major determinant in macrovascular disease

MICROVASCULAR COMPLICATIONS-PATHOGENESIS Usually cells can reduce the movement of glucose inside,when they are exposed to increase glucose levels so that their internal glucose concentration stays constant.In contrast ,the cells damaged by hyperglycemia are those that cannot do this efficiently.Thus ,diabetes selectively damages cells,like endothelial cells and mesangial cells.

Increased intracellular glucose leads to the formation of advanced glycosylation end products(AGE’s) via the nonenzymatic glycosylation of cellular proteins.this promotes glomerular dysfunction ,reduce nitric oxide synthesis,induce endothelial dysfunction and alter extracellular matrix composition and structure

Hyperglycaemia increases glucose metabolism through the sorbital pathway.Increased sorbital concentrations affect several aspects of cellular physiology and may lead to cellular dysfunction

Hyperglycaemia increases the formation of diacylglycerol leading to activation of protein kinase-c ,which in turn affects a variety of cellular events that lead to DM related complication

Hyperglycaemia increases superoxide production by the mitochondria and causes oxidative stress on the cells

DIABETIC RETINOPATHY-Diabetic retinopathy is characterized by gradually progressive alterations in the renal microvasculature,leading to areas of retinal non-perfusion,increased vasopermeability, and pathologic intraocular proliferation of retinal vessels It is one of the leading causes of blindness in the world and the chance of loosing the sight is about 25 times higher compared to normal individuals. Diabetic retinopathy occurs in both type 1 and 2 DM.It has been shown that nearly all types 1 and 15% of type 2 diabetes mellitus will develop diabetic retinopathy after 15 years of duration of diabetes mellitus. In india with the epidemic increase in type 2 diabetes mellitus,as reported by WHO ,diabetes mellitus is fast becoming an important cause of visual disability.The prevalence of diabetic retinopathy varies in type 1 and type 2 DM.According to EURODIAB IDDM complications study,the prevalence ranged between 25-60%.In india the prevalence was 14%. Two other studies,reported overall prevalence of diabetic retinopathy as 22.4% and 26.8%.Among the known diabetic subjects ,the overall prevalence was 20.8%.

Duration of diabetes mellitus and degree of glycemic control are the best predictors of the development of retinopathy.Non proliferative retinopathy is found in almost all individuals who had diabetes for more than 20years(25%incidence with 5years and 80% incidence with 15years of type 1DM)

Diabetic retinopathy is classified into two stages-Nonproliferative and Proliferative.Non proliferative diabetic retinopathy usually appears late in the first decade or early in the second decade of the disease and is marked by retinal vascular aneurysms,blot hemorrhages and cotton wool spots.The pathophysiologic mechanisms invoked in non proliferative retinopathy include loss of retina: pericytes,increased retinal vascular permeability, alterations in renal blood flow and abnormal retinal microvasculature all of which leads to retinal ischaemia.The appearance of neovascularization in response to retinal hypoxia is the hallmark of proliferative diabetic retinopathy.These newly formed vessels appear near the optic nerve or macula and rupture easily leading to vitreous haemorrhage,fibroses and finally retinal detachment.The more severe the non proliferative changes the greater the chance of evolution to proliferative retinopathy in five years American Academic of Opthalmology classification-

Non Proliferative Diabetic Retinopathy(NPDR)1)Mild NPDR Atleast one retinal microaneurysm and one or more of the following:retinal haemorrhage,hard exudate,soft exudate2)Moderate NPDR Hemorrhages or microaneurysms or both in atleast one quadrant and one or more of the following: soft exudates, venous beading and IRMA3)Severe NPDR Hemorrhages or microaneurysms or both in all quadrants, venous beading in two or more quadrants, IRMA atleast in one quadrant

PDR-1)Early PDR-One or more of the following-NVE-NVD-Vitreous or preretinal haemorrhage-NVE<⅟2 disc area

2)High risk PDR-One or more of the following-NVD>⅟4-⅓ disc area

-NVD with vitreous or preretinal haemorrhage-NVE>⅟2 disc area.Preretinal or vitreous haemorrhage

3)Advanced PDR-Tractional retinal detachment

Note-NVE-Neovascularisation elsewhere NVD-Neovascularisation disc IRMA-Intraretinal microvascular abnormalities

- Kanskis classification of diabetic retinopathy

1)Background diabetic retinopathy a) Haemorrhages(Dot and Blot) b)Microaneurysms(located in inner nuclear layer) c)Hard exudates( located in between inner plexiform and inner nuclear layer) d)Retinal edema (located between outer plexiform and inner nuclear layer)

2)Preproliferative a)vascular changes(beading ,looping) b)Dark blot hemorrhages c)cotton wool spots d)intraretinal microvascular abnormalities e)shunt vessels

3)Proliferative a)Neovascularization b)fibrous proliferation c)Vitreous detachment and haemorrhages

4)Maculopathy a)Focal b)Diffuse c)Ischaemic

Clinical features-are hemorrhages or microaneurysms,cotton wool spots,hard exudates, intraretinal microvascular abnormalities(IRMAs) and venous calibre abnormalities(VCABs) such as venous loops, venous tortuosity and venous beading

Symptoms-blurred vision, central vision and metamorphosia as a result of foveal involvementblack spots,floaters or sudden visual loss due to vitreous haemorrhage.

Eye examination-Screening of the eye by fundoscopic examination every year once diabetes has been diagnosed and more frequent checkups after diabetic retinopathy has been diagnosed

Diabetic retinopathy is a sight threatening complication of DM and is one of the leading causes of acquired blindness. UKPDS study revealed that for every percentage reduction of HbA1c(eg from 8 to 7%) there was a 35% reduction in risk of retinopathy Hypomagnesemia and poor diabetes control are one of the series of risk factors related to the development and progression of diabetic retinopathy.In our cross sectional study we will correlate diabetic retinopathy and HBA1C and serum magnesium

Diabetic nephropathy

Diabetic nephropathy is clinically defined by persistent proteinuria greater than 500mg/24 hours in

a person with diabetic retinopathy without other renal disease

Epidemiology

Diabetes has become the most common single cause of end stage renal disease (ESRD)

worldwide.About 20-30% of patients with type 1 or type 2 diabetes mellitus develop evidence of

nephropathy, but in type 2 diabetes a smaller fraction of these progress to ESRD.However because

of much higher prevalence of type 2 diabetes mellitus ,these patients constitute over half of the

patients with nephropathy needing dialyses

The diabetic nephropathy progresses from appearance of low but abnormal levels of (≥30mg to

299mg/day or 20µg/min) albumin in urine (stage of microalbuminuria) to stage of

macroalbuminuria/clinical albuminuria(≥300mg/dl or ≥200µg/min) to ESRD.Progress from

microalbuminuria to macroalbuminuria usually takes 10-15years. ESRD develops in 50% of type 1

diabetic individuals with clinical nephropathy within 10years and in 75% by 20years.But in type 2

diabetes mellitus,even after 20 years of overt nephropathy only 20% progress to ESRD

Clinical features-

Symptoms-

1.Oliguria

2.Anuria

3.Puffiness of face

4.Distension of abdomen

5.Pedal oedema

NEPHROPATHY IN TYPE 1 DIABETES

The course can be followed by two main variables: Proteinuria and GFR.

There are five distinct stages:

I) Stage 1- Glomerular hyper filtration and renal enlargement.

II) Stage 2-Early glomerular lesions or silent stage with normal albumin excretion. Early

glomerular lesions, consisting of glomerular basement membrane thickening and

mesangial matrix expansion are characteristic of this stage. These structural changes

appear 18 to 36 months after onset of type 1 diabetes and may become prominent after

3.5 to 5 years.

During this stage of morphologic changes , microalbuminuria, seen only after exercise or

during episodes of very poor metabolic control

III) Stage 3- Incipient diabetic nephropathy or microalbuminuric stage

Microalbuminuria defined as urinary AER greater than 30mg/24 hours or 20

microgram/minute and less than 300mg/24 hours or 200 microgram/minute, represents

the first laboratory evidence of diabetic renal disease. Total daily AER varies greatly and is

increased by hypertension , strenuous exercise, fever, poor glycemic control , and

congestive heart failure. Therefore, a diagnosis of incipieny diabetic nephropathy is made

only when microalbuminuria is detected in atleast two of three urini specimens over

several months

IV) Stage 4-Clinical or overt diabetic nephropathy:Proteinuria and falling GFR

Albuminuria greater than 300mg/24 hours , relentless decline of renal function , and

hypertension define the fourth stage of diabetic nephropathy.this stage, though variable,

usually occurs 15 to 20 years after onset of type 1 diabetes and after 5 or more years of

diagnosed type 2 diabetes. The amount of urinary protein can be as little as 500mg. but it

can reach massive proportions, such as 20 to 40 gm/24 hours.

V) Stage 5- End stage renal diease.

NEPHROPATHY IN TYPE 2 DIABETES

Although renal structural changes and severity of target organ damage are similar in both types

of diabetes, delayed diagnosis has complicated the construction of the natural history of diabetic

renal disease in type 2 diabetes.

Other diabetic associated renal disease:

1. Urinary tract infection

2. Papillary necrosis

3. Radiocontrast induced renal failure

4. Emphysematous pyelonephritis .

Screening for microalbuminuria-

A test for the presence of urinary microalbumin should be performed at diagnoses in patients with Type 2 diabetes mellitus and after 5years of disease duration in those with type 1 diabetes mellitus,then repeated annually.Screening for microalbuminuria can be performed by three methods

1)Measurement of the albumin to creatinine ratio in a rapid spot urine collection2)24 hr Urine collection and measurement of albumin excretion3)Timed (eg 4hr or overnight) collection

24 hr collection of urine is most reliable

Category Spot collection (µgm/mg creatinine)

24 Hr collection (mg/24 hrs)

Timed collection (µg/min)

Normal <30 <30 <20Microalbuminuria 30-299 30-299 20-199Clinical albuminuria ≥300 ≥300 ≥200

Glycemic Control

Large-scale, prospective trials provide compelling evidence thatintensive glycemic control prevents diabetic nephropathy. The DCCT, whichstrived for near-normoglycemia in patients with type I diabetes, showed a 39%reduction in the risk of developing microalbuminuria and a 54% reduction inthe occurrence of albuminuria. The UKPDS, comparing intensive blood glucosewith conventional therapy in type 2 diabetes, found a 25% risk reduction inmicrovascular complications, including progressive nephropathy.

DIABETIC NEUROPATHY

Clinical picture of diabetic neuropathy varies widely. Onset may be abrupt or insidious,

progress slow , rapid or episodic, sensory symptoms predominate in the majority.

Diabetic neuropathy occurs in approximately 50% of individuals with long standing type 1 or

type 2 diabetes.As with other complications of diabetes,the development of neuropathy

correlates with the duration of diabetes and glycemic control

Natural history-

The natural history of diabetic neuropathy separates patients into two distinct entities:

1. Those who progress gradually with increasing duration of diabetes mellitus and

2. Those who have a relatively exclusive onset and experience remission almost

completely. Sensory and autonomic neuropathies generally progress

mononeuropathies, radiculopathies and acute painful neuropathies , although

symptoms are severe , are shortlived and tend to recover.

Epidemiology

Assessment of prevalence, incidence and risk factors have remained the most confusing

aspects of diabetic neuropathy. problems arise due to the lack of consensus on what

constitutes diabetic neuropathy. in other words the definition of this disorder. Variations in

the reported prevalence of diabetic neuropathy are very wide:0-95% according to Garland II

and 10-100% according to Milton J. These astounding results are mostly due to adaption of

different criteria for diagnosis and partly due to difference in age and duration of diabetes

in the population examined .Certain highly suggestive signs such as diminished or loss of

Achilles tendon reflex, decreased vibration perception and atrophy of distal musles can be

elicited in a proportion of ageing subjects in the absence of diabetes. So 'puzzling' of the

problems that a comprehensive compendium of 'Diabetes Data' by national institute of

health (USA) has not covered neuropathy because of lack of reliable data on its occurrence

in population with diabetes.

ClinicopathologicaI classification of diabetic neuropathy

Symmetric-

1)Distal ,primarily sensory polyneuropathy

2)Autonomic neuropathy

3)Chronic proximal motor neuropathy

Assymetric-

1)Acute or subacute proximal motor neuropathy

2)Cranial mononeuropathy

3)Truncal neuropathy

4)Entrapment neuropathies

Watkins and Edmonds classification-

1)Progressive Neuropathies

Chronic sensory motor neuropathy

Autonomic neuropathy

2)Reversible Neuropathies

Mononeuropathies

-Proximal motor neuropathy(Amyotrophy)

-Cranial nerve palsies (3,4,6)

-Truncal radiculopathies

Acute painful neuropathies

3)Pressure Palsies

-Carpal tunnel syndrome

The most common form of diabetic neuropathy is distal symmetric polyneuropathy.Most

frequently presents with distal sensory loss.Hyperaesthesia,paresthesia and dysesthesia can

also occur

Painful neuropathies may develop in these patients.Both an acute (lasting<12months) and a

chronic form of painful diabetic neuropathy can develop.Individuals with long standing type

1 or type 2 diabetes may develop autonomic neuropathy.

Diabetic Autonomic neuropathy

Postural hypotension

Resting tachycardia

Impotency and erectile failure

Retension and incontinence of urine

Poor urine stream

Constipation and fecal incontinence

Oesophagal and gastroinestestinal dysmotility

Pupillary immobility

Impaired sweating

Snoring and apnea

The role of glycaemic control-

Retrospective and prospective studies have suggested a relation between hyperglycaemia

and the development of diabetic peripheral neuropathy. Partanen et al, in a long term

cohort study of type diabetic patients reported that electrophysiological abnormalities in the

lower limb can be increased from 8% at base line to 42% at 10 years. The UKPDS, which was

initiated in 1977 showed that , control of blood glucose was associated base improvement in

the vibration perception.

Thus, it can be concluded that optimal glycaemic control in type 2 diabeties, whether

achieved by insulin, oral hypoglycaemic agents or occationally diet should be the target in all

patients.

GLYCATED HEMOGLOBIN (HbA1c):

Hemoglobin A (Hb A) constitutes 90% haemoglobin of adults and children above 6 months age.When Hb A is passed through a chromatographic column it seperates into Hb Ao,the major component and minor components-Hb A1a,HbA1b and HbA1c collectively called HbA1 HbA1c is the most abundant of the minor haemoglobin components.This is structurally identical to Hb A,except for a hexose group linked to the N-terminal amino acid (valine) of the beta chain.Hence this is called “ Glycosylated haemoglobin or GHb Normal value of GHb is 4-8 percent and depends on methodology and varies from lab to lab.

Strucuture of HbA1c- synthesis of HbA1c involves post translational, non enzymatic slow glycosylation of HbA within the RBC, occurring continuously throughout its 120days life span in the circulation Formation of HbA1c –a)initially the formation of a weak attachment between the glucose and amino group of HbA by the way of an Aldamine (Schiff base). So called PreHbA1c.This step is rapid and reversibleb)There is a molecular rearrangement of Aldamine(Amadori reaction ) with the formation of a ketamine in which the glucose molecule is finally attached to the Hemoglobin to form HbA1c. This step is slow and irreversible

From structural and biosynthetic information available this is clear that HbA1c is formed slowly and almost irreversibly by the condensation of glucose and Hb in RBC. With simultaneous accumulation of HbA1c it is evident that the amount of this component should be a reflection of average glucose concentration seen by RBCs during their life span

Direct evidence for this relationship derives from atleast three lines of evidence which include ,

1)A reduction of HbA1c levels after diabetic patients are brought under optimal blood glucose control2)A plethora of studies which demonstrate a relationship between HbA1c levels and a variety of indices of diabetic glycemia and3)Excellent correlations between clinical evaluation of the patients level of control and HbA1c level

1% HbA1c was reported to represent 35 mg% of blood glucose levels and like wise formulae are derived from univariate analysis such as HbA1c = 2.07x (mean blood glucose).596. These formulae are not for general use because of acute fluctuations in blood glucose and methodology differences.

Clinical significance of HbA1c-

1)HbA1c:an indicator of metabolic control of diabetes-

When properly assayed ,the percent of HbA1c provides a good retrospective, cumulative index of glycemic control for the preceeding 3 months period

2)HbA1c: A too for diagnoses

1-A spot test for screening and diagnosis of diabetes 2-A simple test for selection and followup of true border line diabetics 3-Its estimation on post-mortem specimens can provide an evidence of history of diabetes 4-A useful parameter to differentiate stress induced hyperglycemia from diabetic hyperglycemia

3)HbA1c and pregnancy

1-Higher evidence of major congenital anamolies in the progeny of women with elevated HbA1c in the early pregnancy was observed in retrospective study 2-HbA1c could be a predictor of birth weight

4)HbA1c Vs vascular complications Elevated HbA1c was observed in diabetic neuropathy suggestion hyperglycemia or a related metabolic abnormality as an important factor in establishing neuropathy Several studies showed a positive correlation between HbA1c and retinopathy,neuropathy and platelet aggregation

Effect of glycosylation of function of haemoglobin- Glucose in HbA1c is attached to N-terminal of beta chain of HbA which also forms the site for 2,3 Diphosphoglycerate(2,3 DPG), a regulator of Hb function.HbA1c has high affinity for oxygen.Thus ,in diabetics elevated HbA1c and a relative deficiency of 2,3DPG may result in decreased oxygenation in tissue.This forms one of the hypothesis for the pathogenicity of neuropathy and other microvascular complications

Glycated hemoglobin (HbA1c) concentration represents the integrated values of glucose over preceding 6 to 8 weeks since the rate of formation of glycated hemoglobin is directly proportional to the concentration of glucose in blood. Other advantage of glycated hemoglobin values for assessing glucose control is because HbA1c is free of day-to-day glucose fluctuations and are unaffected by exercise or recent food ingestion. Measurement of HbA1c is considered as gold standard for monitoring chronic glycemia in diabetic patients. It indicates an average blood glucose levels over the past 3 months. Its close association with the risk of development of long-term complications is well established. Hence, monitoring of glycemic status has been considered as cornerstone of diabetes care. The importance of monitoring glycemia has been established by studies proving that there is a direct relationship between mean blood glucose and the development and progression to chronic diabetic complications. The results of monitoring are used to assess efficacy of therapy and to guide adjustments in lifestyle to achieve best possible glycemic control The DCCT found that when 1441 patients with type 1 diabetes were randomised to intensive rather than conventional treatment, their median HbA1c was 7.3% compared with 9.1% throughout the 6.5 years average follow up period. The subsequent risk of developing retinopathy in the intensively treated group was reduced by 76%, the risk of developing proteinuria was reduced by 54%, and the risk of clinical neuropathy was reduced by 60%.Looked at from the perspective of HbA1c ,the risk of microvascular complications in the two patient groups rose exponentially as the HbA1c value increased with no threshold short of normal glycemia below which patients with type 1 diabetes did not develop microvascular complications at all

HbA1c levels-Less than or equal to 5.6% is a very healthy HbA1c levelBetween 5.7% and 6.4% is a fair HbA1c level and needs work to improveBetween 8% and 10% indicates blood glucose level is too highAbove 10% indicates blood glucose levels are extremely high

Correlation of HbA1c with average blood glucose-

Average blood glucose(mg/dl)=[28.7xHbA1C(%)] - 46.7

Average blood glucose (mmol/L)=[1.59xHbA1C(%)] – 2.59

Correlation of HbA1c with average blood glucose-HbA1c(%) Mean blood glucose(mg/dl) Mean blood glucose(mmol/L)5 97 5.46 126 7.07 154 8.68 183 10.29 212 11.810 240 13.411 269 14.912 298 16.5

Advantages of HbA1c for screening and diagnosis of Type 2 Diabetes Mellitus.1) There is no need for fasting.

2) HbA1c is less affected by day to day variation in plasma glucose. It is not affected by the duration of the diabetes ,sex and weight status

3) There is less biological variability associated with HbA1c than with fasting plasma glucose testing.

4) HbA1c measures chronic glycemic exposure rather than acute value, therefore providing a more relevant view of long-term glycemia and future risk of complications.

5) HbA1c has simpler sampling and analysis requirements.

Disadvantages of HbA1c estimation-

1)The rate of formation of glycosylation is much faster than its disappearance

2)Results very depending on the method used

3)No internationally accepted standard is as yet available

Limitations of HbA1c for diagnosis of Type 2 Diabetes Mellitus.

1)Falsely low values are obtained in people:

Increased destruction of RBCs-Hemolytic anaemia

Active erythropoiesis as in pregnancy

Taking iron, vitamin B12 or any product that temporarily increases RBC production.

Who have undergone blood transfusion any time in the previous 3 months. 2) Falsely high values obtained in people: Iron deficiency anemia.

Vitamin B12 or folate deficiency.

Alcoholism or chronic renal failure

Hemoglobinopathies like sickle cell anemia

Hyperlipidemia

METHODS FOR MEASURING GLYCOSYLATED HEMOGLOBIN

1)Chromatographic method (Kynoch and Lehmann)

2)Colorimeteric Method(Fluckiger and Winterhalter)3)Electrophoretic method

4)Radioimmunoassay

Among these chromatographic method has been widely used to estimate HbA1c.

It is a simple and rapid method (microchromatography).It has better resolution and more precision .It requires small amount of sample and no special equipment.Its cost and use of cyanide as buffer are the main disadvantages

Serum Magnesium

Magnesium is the fourth most abundant cation in the body and the second most plentiful intracellularly, after potassium. Adult human body contains 21-28gms(approximately 2000mEq) of magnesium. Approximately 60% of total body magnesium is located in the bone and remainder is in the soft tissues. This soft tissue intracellular compartment comprises about 38% of total body magnesium; relatively higher concentrations are found in the liver and skeletal muscle (15-20mEq/kg). Less than 2% is present in extracellular (ECF) compartment.

Serum concentration of magnesium ranges from 1.7 to 2.4 mg/dl (0.7-1.0mmol/L). The plasma concentration in healthy adults remain remarkably constant. It is important to point out that limits of the normal range deviate from the mean by less than 15 percent, indicating that the serum concentration is maintained by sensitive control mechanisms that are poorly understood at present.

The average daily intake of magnesium is of the order of 25 mEq (140-360mg/day). Less than 40% of dietary magnesium is absorbed throughout the small intestine predominantly in the ileum. Elimination is predominantly renal and averages 100mg/day. The threshold for urinary excretion is near the upper limit of normal range. Thus when serum levels rise above 2.4mg/dl, magnesium excretion increases dramatically. Conversely, the kidney retains a strong capacity to reabsorb magnesium in condition of magnesium depletion, and the main site for reabsorption is the thick ascending loop of Henle. Several factors may impair renal reabsorption , such as volume expansion, hypercalcemia and diuretic administration (eg. osmotic, thiazide or loop).

BIOCHEMICAL IMPORTANCE OF MAGNESIUM-

Magnesium is an activator of a host of enzyme systems that are critical to cellular metabolism. Prominent are the enzymes that hydrolise and transfer phosphate groups, esp. those involved in the reactions involving adenosine triphosphate (ATP). As ATP is required for glucose utilisation, fat, protein, nucleic acid and coenzyme synthesis, muscle contraction and other reactions, by inference the activating effect of magnesium extends to all these functions.

Additionally, magnesium is required as a cofactor for oxidative phosphorylation in the mitochondria.

Magnesium contributes to macromolecular structure as in stabilising the organization of DND, RNA and ribosomes. Magnesium is further involved in protein synthesis by contributing to the binding of messenger RNA to the 70s ribosome.

Interrelations of major biologic cations

Magnesium is generally found in high concentrations within the cell, whereas intracellular calcium content is low. The ratios are inverted in extracellular fluid.

Variations in dietary calcium does not affect the absorption of magnesium. magnesium reabsorption in renal tubules is inhibited by hypercalcemia. The intracellular phosphate concentration is usually parallel to magnesium

concentration.Hormonal factors

Increasing serum magnesium: Parathyroid hormone Glucogon 1,25(OH)2 Calcitriol

Decreasing serum magnesium

Aldosterone Vasopressin (ADH) Thyroxin Calcitonin

HYPERMAGNESEMIA

Hypermagnesemia is rarely seen in the absence of renal insufficiency as kidney can excrete large amounts of magnesium (upto 250 mmol/d)

Causes of hypermagnesemia

Impaired magnesium excretion --Renal failure

--Familial hypocalciuric hypercalcemia

Excessive magnesium intake --Cathartics

--Antacid preparations

--Parenteral magnesium administration (eg. magnesium sulphate in PIH)

Rapid magnesium mobilisation from soft tissues --Trauma

--Excessive burns

--Shock, sepsis

--Post –cardiac arrest

Other disorders --Adrenal insufficiency

--Hypothyroidism

--Hypothermia

Clinical features

The most prominent clinical manifestation of hypermagnesemia are vasodilation and neuromuscular blockade which appear at serum magnesium concentrations >4.8mg/dl(>2mmol/L). Hypotension, refractory to vasopressors and volume expansion may be an early sign. Lethargy and weakness may progress to respiratory failure, paralysis and coma with hypoactive tendon reflexes (at >4mmol/L).Gastrointestinal hypomotility or ileus may occur. Prolongation of PR, QRS intervals and heart blocks at serum magnesium(S.Mg) levels approaching10mmol/L, asystole.

HYPOMAGNESEMIA

Signifies depletion of body magnesium (Mg) stores(0.5 -1mmol/kg). Hypomagnesemia has varied etiology. Dietary Mg deficiency occurs in the setting of alcoholism.

Causes

1. Impaired intestinal absorptiona. Primary infantile hypomagnesemiab. Malabsorption syndromesc. Vitamin D deficiency

2. Increased intestinal lossesa. Protracted vomiting or diarrhoeab. Intestinal drainage,fistulae

3. Impaired renal tubular absorptiona. Genetic Mg wasting syndromes

i. Gittleman’s syndromeii. Barter’s syndromeiii. Na-K ATPase g-subunit mutations

b. Acquired renal diseasei. Tubulointerstitial diseaseii. Post obstruction/ATN (diuretic phase)iii. Renal transplantation

c. Drugsi. Ethanolii. Diuretics(loop, osmotic, thiazide)iii. Cisplatin, Cyclosporineiv. Aminoglycosides, Amphotericin B

4. Metabolic causesi. Hyperaldosteronism

ii. SIADHiii. Diabetes mellitusiv. Metabolic acidosisv. Hypercalcemiavi. Hyperthyroidism

5. Othersi. Pancreatitisii. Excessive sweatingiii. Osteoblastic metastases

Prolonged nasogastric suction, parenteral fluids, infectious diarrhoea, steatorrhoea, inflammatory bowel disease may cause hypomagnesemia

Frequency

Risk of incidence is as follows:

2% in general population 10-20% in hospitalized patients 50-60% in ICU patients (nutrition, diuretics, hypoalbuminemia and aminoglcosides

may play an important role) 30-80% in alcoholics

25% in diabetic outpatientsSex

Incidence is equal in males and females

Clinical features

History

Clues to the presence of hypomagnesemia can be found by obtaining history of potential causes

Complaints related to hypomagnesemia are non specific Patients may report weakness, muscle cramping or rapid heartbeats Alterd mental status(irritability, apathy, psychosis, delirium) may be present in

severe cases. Less severe cases may result in vertigo, ataxia, depression and seizure activity.

Physical signs

Symptoms and signs appear only when S.Mg levels are <1.2mg/dl (0.5mmol/L). The primary clinical findings are neuromuscular irritability, CNS hyperexcitability and cardiac arrhythmias.

Signs

Hyperactive deep tendon reflexes Muscle cramps Trousseau and Chvostek signs Dysphagia due to esophageal dysmotility Irritability/disorientation Ataxia, nystagmus or seizures (at levels<0.8mg/dl) Paroxysmal atrial and ventricular dysrrhythmias

ECG

Mg depletion can induce changes in the ECG.Findings are non specific. Moderate depletion (1.2-1.7mg/dl ) leads to widening of QRS complex, flattening/inversion of T and U waves.

Cardiac arrhythmias may occur including sinus tachycardia, other supraventricular tachycardia and ventricular arrhythmias.

Lab studies

The serum magnesium level is not a reliable determinant of total body magnesium depletion, because only a small fraction of magnesium in the body is extracellular. Nevertheless, a deficiency of magnesium is clearly present if serum level is low.

Serum magnesium levels may be estimated by several methods:

Neutron activation analysis Atomic absorption spectrometry Ion selective electrodes(ISE) Equilibrium dialysis Calmagite dye methodCalcium, potassium and phosphorus levels must be assessed.

BUN and creatinine levels

Blood glucose levels.

MAGNESIUM AND DIABETES

Magnesium has a fundamental role in carbohydrate metabolism and diabetes mellitus has been suggested to be the most common metabolic disorder associated with magnesium deficiency, which has 25-39% prevalence in diabetes.

The clinical implications of magnesium deficiency as it relates to diabetes are many. Hypomagnesemia can be a consequence of hyperglycemia (as seen in increased urinary magnesium excretion along with glycosuria) and a cause of insulin resistance. The association between diabetes mellitus and hypomagnesemia is compelling for its wide ranging impact on diabetic control, complications and untimely therapy.Although poor glcemic control is associated with magnesium deficiency, it’s not simply induced by hyperglycemia and is not corrected by improvement in metabolic control alone. Magnesium depletion has been linked to the development of diabetic retinopathy. Of greater importance is tha association between magnesium depletion and hypertension, thrombotic tendency, insulin resistance and Reaven-Modan syndrome, a distinct clinical entity that links diabetes mellitus, hyperinsulinemia, hypertension and increased thrombotic tendency – all cardiovascular risks.

Causes of hypomagnesemia in diabetes mellitus

Initially the cause was attributed to (1) osmotic renal losses from glycosuria, (2) decreased intestinal magnesium absorption and (3) redistribution of magnesium from plasma to RBCs caused by insulin effect. Recently a specific tubular magnesium defect in diabetes has been postulated. A reduction in tubular absorption of magnesium results in hypermagnisuria. The exact site of resorptive defect is not yet defined. This is postulated to be either in the thick ascending loop of Henle or more distally. The cause of the defect is unclear.

insulin treatment has been shown to correct diabetic renal magnesium losses. Garland noted that delayed insulin treatment may be less effective in correcting the renal losses, suggesting some irreversible component.

The role of magnesium in insulin action

Magnesium is involved in multiple levels in insulin secretion, binding and activity. Magnesium (Mg) is a critical cofactor of many enzymes in carbohydrate metabolism Cellular magnesium deficiency can alter the activity of membrane bound Na-K ATPase which is involved in maintenance of gradients of Na and K and in glucose transport. Low levels of Mg can reduce secretion of insulin by pancreas.

In addition to these effects of Mg, Mg deficiency has been shown to promote insulin resistance in multiple studies. In isolated soleus muscle , Mg deficiency inhibits both basal and insulin stimulated glucose uptake.This insulin resistance is a post receptor defect and may be linked to calcium mediation of insulin signal. In diabetes there is direct relationship between S. Mg level and cellular glucose disposal, that is independent of insulin secretion. This change in glucose disposal has been shown to be related to increased sensitivity of tissues to insulin in the presence of adequate Mg levels.

In a recent study, the cellular uptake of Mg, which is normally stimulated by insulin,was shown to be attenuated in diabetics. There is also evidence that Mg deficiency itself produces insulin resistance. Nadler et al. studied 16 non diabetic subjects and found that insulin sensitivity fell after induction of Mg deficiency.

Likewise , early non diabetic subjects were shown to have improved glucose handling, when they received Mg supplements for 4 weeks.There was adirect relationship between intracellular Mg level and glucose metabolism, thus implicating Mg deficiency in the insulin resistance of aging. In non diabetic obese subjects insulin resistance was found along with low Mg levels, when compared with non obese subjects, again highlighting the association between hypomagnesemia and insulin resistance.

An intriguing theory suggested by Tonyai et al. is that a low erythrocyte Mg content can alter membrane viscosity and this may impair the interaction of insulin with its receptor on the membrane. Paolisso et al. were able to correct the increase in erythrocyte microviscosity with long term Mg administration.

Role of Mg deficiency in diabetic end organ damage

Mg deficiency has been found to be associated with diabetic microvascular disease. Hypomagnesemia has been demonstrated in patients with diabetic retinopathy, with lower Mg levels , predicting a greater risk of severe diabetic retinopathy. Mg depletion is also found to play a role in the pathogenesis of diabetic polyneuropathy. Corsonello et al. have reported an association between diabetic nephropathy and Mg depletion.Micro albuminuria and clinical proteinuria , as well as poor glycometabolic control and hypertriglyceridemia are associated to relevant alterations in serum ionised Mg. Mg

depletion has been associated with multiple cardiovascular implications: arrhythmias, vasospasm, hypertension and platelet activity.

Three exciting theories link diabetes and its vascular complications to hypomagnesemia. The inositol transport theory, the ionic hypothesis of metabolic disease and oxidative stress theory.

Grafton et al. have focussed on the inositol transport theory. It has been one of the favoured explanations for the origin of diabetic complications .The theory suggests that hyperglycemia induces increased activity of the enzyme aldose reductase which leads to the intracellular accumulation of sorbitol. The accumulated sorbitol inhibits transport of inositol , leading to a decrease in intracellular inositol and inhibition of N a-K ATPase activity. The data of Grafton et al. show that hypomagnesemia causes a decrease in affinity of the inositol transport protein for inositol, leading to a two fold reduction in rate of inositol transport and accelerated development of diabetic complications.

The association between Mg deficiency, Essential hypertension, insulin resistance, hyperinsulinemia and ischaemic heart disease (Reaven Modan syndrome) may be explained by the ionic hypothesis of cardiovascular and metabolic disease proposed by Resnick. Suppression of intracellular free Mg and an increase of intracellular free calcium are linked in these varied biologic processes: hypertension, decreased insulin secretion and insulin resistance. Therefore, Resnick proposedthat the ‘primary’ defect in all organ systems is an abnormality of cellular ion handling.Mg deficiency would be the link. Since its role in maintain cellular pumps necessary for peripheral vascular tone (Na-K ATPase and calcium activated K channels) would be diminished. Indeed, Mg deficiency may lead to a reduction in insulin action by increasing free intracellular calcium levels.

Diabetes is a state of increased free radical activity. Lipid peroxidation of cellular structures, a consequence of free radical activity , is thought to play an important role in aging, atherosclerosis and late diabetic complications. In recent years, there has been growing interest in Mg and its correlation with oxidative states. Weglicki et al. have proposed that during Mg deficiency, natural antioxidant deficiencies present in mammalian tissues against oxidative stress may be compromised. Mg deficiency has been shown to impair functions of natural antioxidants such as glutathione, ascorbic acid and vitamin E

EVIDENCE FOR EFFICACY OF MAGNESIUM SUPPLEMENTATION IN DIABETES MELLITUS

There is accumulating evidence that repletion of Mg can ameliorate the insulin resistance, platelet reactivity and other cardiovascular risk factors associated with hypomagnesemia and diabetes mellitus.

In a study of 16 diabetics and 30 healthy controls, oral replacement with magnesium hydroxide at a dose of 250mg twice daily resulted in decreased insulin requirements in the diabetic patients. In elderly type 2 diabetics, Paolisso et al. demonstrated that oral Mg supplementation given for 4 weeks resulted in lower fasting plasma glucose levels, increased plasma Mg levels and a slight, but statistically significant increase in beta cell response to glucose and arginine. The benefit of long term Mg supplementation is an improvement in both glucose induced insulin response and insulin action, decreasing insulin resistance and improving glucose haemostasis.

In type2 diabetics, oral supplementation of Mg has been shown to decrease platelet reactivity, lower systolic blood pressure by 7mmHg and to result in a beneficial effect on lipid profile.

CLINICAL APPROACH TO MAGNESIUM SUPPLEMENTATION IN DIABETES MELLITUS

The consensual conference on Mg supplementation sponsored by the American Diabetes Association warrants a more interventionist approach to hypomagnesemia.

There are no accurate tests clinically available to determine intracellular Mg depletion routinely in diabetes. With 99% of body stores of Mg being intracellular, low S. Mg level is an insensitive, yet precise measure of total body stores.

Certainly patients at risk for hypomagnesemia should have S.Mg measured. Thisincludes diabetics with clinical states known to be associated with hypomagnesemia such as acute myocardial infarction, ketoacidosis, alcohol abuse, long term parenteral nutrition, chronic diarrhoea or use of diuretics or digoxin. Additionally, patients at high risk of cardiac events such as arrhythmia and vasospasm, should be considered for Mg repletion. Whether the broader range of Mg related abnormalities such as hypertension, hyperlipidemia, and insulin resistance of diabetes itself should be treated with repletion , requires a randomised clinical trial to determine.However ,each patients individual risksfor hypomagnesemia, cardiovascular risks and risks related to therapy need to be assessed.

Overt serum hypomagnesemia should always be corrected. If hypomagnesemia is clinically suspected, but cannot be documented by serum levels, a further test with erythrocyte or platelet Mg concentration is necessary.Renal insufficiency , esp. with creatinine clearance of less than 30ml/min is the only factor that precludes dietary supplements.

Mg chloride is the preparation of choice (slow mag) . Doses of 100-600mg/day may be necessary to achieve repletion. Diarrhoea is the dose limiting side effect.

AIM-

to find out the association between microvascular complications of diabetes with HbA1c and its association with S Magnesium,and if there is any co-relation between HbA1c and S Magnesium in a diabetic patient with microvascular complications

OBJECTIVES- To find out the association between microvascular complications of diabetes with HbA1c To find out the association between microvascular complications of diabetes with serum magnesium To check if there is any correlation between HbA1c and Serum magnesium in a diabetic patient with microvascular complications

REVIEW OF LITERATURE- There is a strong evidence to suggest that the development and progression of diabetic retinopathy is influenced by the level of hyperglycaemia The Diabetes Control and Complications Trial (DCCT) randomized patients (n=1441) with type1 diabetes to receive intensive glycemic or conventional therapy with the objective to investigate whether this would prevent or delay the progression of early preproliferative retinopathy and whether tight glycemic control could prevent the progression of early retinopathy to clinically more advanced forms.Conventional treatment comprised one to two daily injections of insulin, without adjustment in daily insulin dose while intensive treatment consisted of three injections of insulin or insulin by an external pump with the goal of achieving normal glycemia,results of over 6.5 years of follow up showed that,compared to conventional treatment group (median HbA1c, 9.1%) incidence of DR reduced by 76%(ƿ<0.002) and progression of DR by 54%(ƿ<0.011) in the intensive treatment group (median HbA1c, 7.2%). Similar beneficial effects of intensive therapy were evident in subgroups by age ,sex, percentage of ideal body weight, duration, level of retinopathy, BP, clinical neuropathy, albuminuria and baseline HbA1c level.Even in the long term ,the rate of DR progression in the intensively treated group remained significantly lower than in the conventional group.Finding of DCCT highlighted the importance of instituting tight glycemic control early in the course of diabetes. HbA1c has long been known to predict the incidence and progression of DR.The severity and the duration of the inadequate glycemic control have been seen to be correlated with a higher risk of increased severity of retinopathy, from non proliferative to proliferative DR. The protective effect of glycemic control on the development and progression of DR has been investigated in both type 1 (WESDR and Diabetes Control and Complications Trial-DCCT) and type 2 diabetic patients (UKPDS)

In the 14 year progression of retinopathy study (WESDR), the prevalence of retinopathy in type 1 diabetic subjects was 12 percent when glycated haemoglobin was (HbA1c) was< 7percent as compared to 40.7 percent when HbA1c levels were > 10 percent and an increased risk of PDR was associated with more severe baseline retinopathy and higher HbA1c levels

In the UKPDS ,the risk reduction in eye complications for every 1 percent decrease in HbA1c was 19 percent.Thus it is observed that long term glycemic control plays an important role in delaying the onset and lowering down the progression of DR

Rema et al have also shown that the visual outcome of laser photocoagulation for eyes with PDR was also dependent on the degree of glycemic control

In the CURES Eye Study a linear trend in the prevalence of retinopathy with increase in quartiles of HbA1c(trend Chi square: 51.6, ƿ < 0.001) from 8.1 percent (HbA1c level <6.9%) to 31.7 percent (HbA1c level >10.3%) was observed. For every 2 percent elevation of HbA1c, the risk for DR increased by a factor of of 1.710 Decrease in HbA1c concentrations by 1% leads to an established reduction by 30%in the risk of microvascular complicationsy, In the study conducted by Bilgin ozmen et al the frequency of DR was 46.6% [ 28.8% have NPDR and 17.8% have PDR]. There was a stastically significant relationship between HbA1c levels and DR (both NPDR and PDR) (p<0.000). The frequency of retinopathy (both background and proliferative ) was 4.8% in the group of diabetics with a meanHbA1c level <6%, 8.7 % in those between 6.1 and 6.9%, 62.8% in those between 7 and 9.9% and 82.2% in those exceeding a mean HbA1clevel of 10%. According to a study conducted in Tamil nadu on Sight Threathening Diabetic Retinopathy (STDR) by Raman R et al the HbA1c value >8.0% was significantly related with STDR. In a screening programme, the cut-off value of HbA1c >8.0% provided a maximum yield of STDR.

According to Klein R et al- A positive relationship between incidence and progression of retinopathy and glycosylated hemoglobin remained after controlling for duration of diabetes, age, sex, and baseline retinopathy. These data suggest a strong and consistent relationship between hyperglycemia and incidence and progression of retinopathy.

In a study by Singh r et al  In diabetic patients with retinopathy, the mean value of HbA1c was higher in proliferative retinopathy than in background retinopathy, but statistical analysis showed this was not significant (P greater than .6).

In a multivariate analysis, each increment of 1 g/dL in hemoglobin was associated with a linear 29% increase in risk for retinopathy in men with type 1 diabetes (95% CI 8% to 54%), and a quadratic 10% risk increase in women (95% CI 0% to 20%), reported Trevor Orchard, MD, of the University of Pittsburgh, and colleagues. "This is the first study, to our knowledge, to show high hemoglobin levels to be predictive of the long-term incidence of proliferative diabetic retinopathy," the researchers wrote in the November issue of Archives of Ophthalmology. Their study analyzed data on 426 participants in the Pittsburgh Epidemiology of Diabetes Complications Study, which began in the late 1980s. Some 18 years of follow-up were thus available.

In a study conducted by Ishrat kareem et al -The average concentration of magnesium in groups I (diabetic without retinopathy), group II (diabetic with retinopathy), and group III (control) were measured as 2.13 ± 0.32, 1.2 ± 0.38 and 2.60 ± 0.37 meq/l respectively. The patients in group II has hypomagnesemia (p < 0.01) when compared to group I. Also group I showed hypomagnesemia (p < 0.01) when compared to group III. Group I,group II and III were also compared with respect to glycosylated hemoglobin, blood glucose,triglyceride and cholesterol levels.

The HbA1c (%) values in group I, group II and group III were measured as 7.62 ± 0.69, 10.48 ±1.22 and 4.99 ± 0.98 respectively. These values were found to be significantly higher (group II p <0.001 and group I p < 0.01) and correlated positively with blood glucose levels

Study done by Mitrabasu et al found that out of 82 diabetic patients studied 42 patient had peripheral neuropathy and 8 patients had autonomic dysfunction that shows 54.0%,and Autonomic involvement in 10.8%,The mean fasting glucose in there study is 149±48mg%,mean HbA1c for development of diabetic neuropathy is 7.9±1.38.

Study done by Kjerosti morkid et al out of 294 diabetic patients they found prevalence of diabetic neuropathy in 19.7%mean duration to develop neuropathy is 9-11 years and mean HbA1c of 8.75+/-2.20

Study done by Ozgur Boyraj et al ,for development of peripheral neuropathy,mean HbA1c is 6.9±1.7 in normal diabetic and in obese it 7.9±1.4

Study done by DCCT trial ,study showed significant reduction in development and progression of clinical neuropathy(64%),autonomic dysfunction(53)% in type 2 diabetic with optimal glycemic control

Study done by UK prospective Diabetes study,control of blood glucose was associated with improvement in vibration perception and reduction of odd ratio for development of autonomic neuropathy

Study done by Jyothi m sawant et al out of 65 patients they studied found that mean FBS in neuropathy patient is 206±68mg%, mean HbA1c is 7.74±1.48

Study done by Arezzo jc et al they found maximum defect will be at sural nerve they also found 1% fall in HbA1c improves the conduction velocity by 1.3M/S

In a study done by Jocelyn Eid Fares et al it was concluded Incipient nephropathy was present in 18 and absent in 99 patients. Mean HbA1C was significantly higher in nephropathy than in non-nephropathy patients. The effect of fluctuations on nephropathy appeared to be more significant in patients with poor metabolic control (HbA1C ⩾ 8%)

A Italian multicentre study RIACE (renal insufficiency and cardiovascular events) concluded that In patients with type 2 diabetes, HbA1c variability affects (albuminuric) CKD more than average HbA1c, whereas only the latter parameter affects DR, thus suggesting a variable effect of these measures on microvascular complications.

Study done by Carter Robert jmc et al concluded Between-individual biological variation in HbA1c, which is distinct from that attributable to MBG, was evident among type 1 diabetic patients in the DCCT and was a strong predictor of risk for diabetes complications. Identification of the processes responsible for biological variation in HbA1c could lead to novel therapies to augment treatments directed at lowering blood glucose levels and preventing diabetes complications.

Study done by Lin CC et al concluded that Annual FPG and HbA1c variations have a strong association with diabetic nephropathy in patients with type 2 diabetes. Whether intervention for reducing glucose variation should be administered needs to be examined in a future study.

IN a study done by Kundu et al concluded, Urinary microalbumin, HbA 1c levels were significantly higher in the cases. Microalbumin levels were linearly correlated to the duration of diabetes and HbA 1c.

In the DCCT, intensive glucose control in patients with type 1 diabetes decreased the incidence of microalbuminuria by 39% in the primary prevention group and decreased the progression from microalbuminuria to macroalbuminuria by 54% in the secondary prevention group.In the United Kingdom Prospective Diabetes Study (UKPDS), there was a 34% decrease in the risk of microalbuminuria in patients with type 2 diabetes treated more intensively for glycemic control.The DCCT benefit in type 1 diabetes was accomplished with an average 20% reduction in HbA1c (9.07.1%). In the UKPDS, the benefit was seen with an 11% reduction in HbA1c(7.97.0%). This suggests that there is benefit to be gained by decreasing hyperglycemia at any level of starting glucose control. Furthermore, it suggests that this benefit can be attained in patients with either type 1 or type 2 diabetes.

According to a study done RP aggrawal et Among 11157 subjects, retinopathy was diagnosed in 32.5%, nephropathy was present in 30.2%, peripheral neuropathy was present in 26.8%, coronary heart disease (CHD) was present in 25.8% and peripheral vascular disease (PVD) was present in 28% of the subjects. Multiple logistic regression analyses showed that age had a significant association with retinopathy, neuropathy, coronary heart disease (CHD) and peripheral vascular diseases (PVD). Duration of diabetes had significant association with the neuropathy, nephropathy and PVD. Higher HbA1C increases the risk of retinopathy, neuropathy and nephropathy

In this observational study, done by Sakaguchi et al we found that hypomagnesemia was significantly associated with progression to ESRD in patients with type 2 diabetic nephropathy but not in those with nondiabetic CKD.

The link between hypomagnesemia and diabetic retinopathy was reported in two cross-sectional studies by Mc Nair et al and Hatwal a et al that involved both “insulin-dependent” patients and patients with type 2 diabetes. Not only did patients with diabetes have lower serum Mg levels compared with their counterparts without diabetes, but also the serum Mg levels among the cohort with diabetes had an inverse correlation with the degree of retinopathy

In a comparative study that involved 30 patients who had type 2 diabetes without microalbuminuria, 30 with microalbuminuria, and 30 with overt proteinuria, Corsonello et al. observed a significant decrease in serum ionized Mg in both the microalbuminuria and overt proteinuria groups compared with the nonmicroalbuminuric group.

Accordingly, in a recent retrospective study,by Pham PC et al showed an association between low serum Mg levels and a significantly faster rate of renal function deterioration in patients with type 2 diabetes was reported

Study done by Kundu et al concluded that Hypomagnesemia and albuminuria individually or in conjunction serve as indicators for dysglycemia and could be used as marker for the risk of development of diabetic retinopathy.

A study done by Baachii xu et al concluded that Serum Mg was inversely associated with the prevalence of microalbuminuria.

METHODOLOGY

Source of data

Patients of diabetes mellitus presenting to department of medicine IGGGH and PGI, Pondicherry during the study period either in inpatient or outpatient basis were considered for study

Sample size: Sample procedure: Cross- sectional study Study Duration:

Inclusion criteria Patients with diabetes mellitus presenting to IGGGH and PGI,Pondicherry. Criteria for establishing diabetes mellitus:

Fasting plasma glucose >=126mg/dl (7.0mmol/dl). (Fasting is defined as no calorie intake for at least 8 hours).

Postprandial plasma glucose >= 200 mg/dl (2 hours after 75 grams of oral glucose).

A1c >= 6.5%. The test performed in a laboratory using a method that is NGSP certified and standardized to the DCCT assay

Exclusion criteria -

Congestive cardiac failure Urinary Tract infection Known hypertensive FeverRenal diseasesOther diseases causing peripheral neuropathy

Exclusion criteria because of HbA1c- Anaemia(Hb<10gm%) Acute metabolic complications Ingestion of antibiotics and aspirin Alcohol intake Uremia Hemoglobinopathies Recent blood transfusion HyperlipidemiaExclusion criteria because of Serum Magnesium- Patients on magnesium supplements or magnesium containing antacids Malabsorption or chronic diarrhoea

Method of collection of data clinical history

• Detailed history regarding the symptoms diabetes like polyuria, polydipsia, polyphagia and weight loss were taken.

• History of microvascular complications taken in detail.

Peripheral neuropathy

Any history of tingling, numbness, burning sensation or any sensory loss.

Autonomicneuropathy

Impotency and erectile failure, retention and incontinence of urine, impaired sweating, snoring and sleep apnea

Diabetic retinopathy

History of blurred vision, black spots, floaters and sudden visual loss

Diabetic nephropathy History of polyuria, oliguria, puffiness of face, distension of abdomen and pedal edema.

CLINICAL EXAMINATION –

Diabetic neuropathy-

Peripheral neuropathy 1. Detection of diabetic peripheral neuropathy by:2 Foot sensitivity testing by Semmes Weinstein monofilament 3 Deep tendon reflex testing by percussion hammer 4 Vibration perception testing by 128 Hz tuning fork. 5 Neurothesiometer

Simmes-Weinstein 10 gm monofilament

Cutaneous pressure perception of the foot was assessed by using 10 gm monofilament. The procedure was explained to the patients.

5.07/10gm Simmes-Weinstein monofilament consisted of a plastic handle supporting a nylon filament. The filament placed perpendicular to the skin of the foot, and pressure was applied until the filament buckles. The filament was held in place for approximately 1 second, then released. The patient was to elicit a “Yes/No response to monofilament pressure and correctly identifies the site of contact. Inability to perceive the 10 grams of force it applies was associated with clinically significant large fibre neuropathy.Like this 9 plantar sites and 1 dorsal site were tested in each foot. Insensitivity to 10 grams monofilament at any one site on either foot was taken as abnormal sensational having significant neuropathy.

Diabetic retinopathy-a.Direct ophthalmoscopic examination of fundus

Fundus examination was done and results were classified as normal, background, pre-proliferative retinopathy and proliferative retinopathy. It was confirmed by ophthalmologist

Background diabetic retinopathy

PDR

Investigations1. Fasting plasma glucose.2. Postprandial plasma glucose.3. Blood routine.4. Urine for proteinuria.5. Blood urea and serum creatinine.6. Urine culture and sensitivity.7. ESR8. Microalbuminuria detection by albumin- creatinine ratio estimation

9. HbA1C 10. S.Magnesium 11. S.Electrolytes12. ESR13. Lipid profile14. GFR

Diabetic nephropathy-Urinary albumin measured by rate nephelometry and urinary creatinine measured by modified Jaffe’s method.

24 hour urinary excretion of albumin- No nephropathy < 30 mg/24hour Microalbuminuria 30-299 mg/24hour Macroalbuminuria(clinical proteinuria) >=300 mg/24hour

Serum Magnesium measurement –Calmagite dye method- Under alkaline conditions, magnesium ions react with calmagite dye to produce a red complex which is measured spectrophotometrically at 530nm. Intensity of the colour produced is directly proportional to magnesium concentration in the serum.To eliminate the interference of calcium during estimation, EDTA is included in the reagent.Heavy metal interference is prevented by the presence of cyanide and a surfactant system is included to prevent protein interferenceProcedure-Three test tubes labelled Blank,Standard and Test are prepared

In test tubes Blank Standard TestCalmagite reagent 1.0ml 1.0ml 1.0mlStandard sample - 10ml -Patient`s sample - - 10mlDistilled water 10ml - -

These test tubes are incubated at room temperature (22-28°C).The absorbance of Test,Standard and Blank are read at 530nm in spectrophotometer.Magnesium concentration is calculated by the formula Magnesium concentration(mEq/L)=(absorbance-blank/standard-blank)x2 Serum magnesium concentration is expressed in mg/dl by linearity of 1mEq/L=1.2mg/dl Normal=1.7 to 2.4 mg/dl Low < 1.7 mg/dl High > 2.4 mg/dl

ESTIMATION OF GLYCATED HEMOGLOBIN

PROFORMA

PRELIMINARY DATA OF PATIENT

Name: Date:

Age/Sex: I.P. No:

Department: Unit:

Ward: Occupation:

Date of admission: Date of discharge:

Address:

PRESENTING COMPLAINTS:

H/o increased frequency of micturition: Yes/No

H/o increased thirst: Yes/No

H/o numbness in feet: Yes/No

H/o burning sensation in extremities: Yes/No

H/o pain in hands: Yes/No

H/o pain in feet: Yes/No

H/o cold sensation in extremities: Yes/No

H/o muscle cramps: Yes/No

H/o paresthesia of both feet: Yes/No

H/o urinary difficulties: Yes/No

H/o blurring of vision: Yes/No

PAST HISTORY:

Previous H/o illness

TREATMENT HISTORY:

PERSONAL HISTORY:

H/o alcohol intake: Yes/No

Duration:

Quantity:

H/o smoking: Yes/No

Duration:

Quantity:

H/o weight loss:

FAMILY HISTORY

Diabetes: Yes/No

Hypertension: Yes/No

GENERAL PHYSICAL EXAMINATION:

Height: cms

Weight: kgs

B.M.I:

Pallor: Yes/No

Icterus: Yes/No

Clubbing: Yes/No

Cyanosis: Yes/No

Lymphadenopathy: Yes/No

VITAL PARAMETERS:

Pulse: BP:

Respiratory rate: Temperature:

SYSTEMIC EXAMINATION:

CENTRAL NERVOUS SYSTEM:

Higher mental functions:

Cranial nerves:

Fundoscopy examination:

Motor system: Right Left

UL LL UL LL

Nutrition:

Tone:

Power:

Coordination:

Involuntary movements:

Gait:

DEEP TENDON REFLEXES

Biceps jerk Triceps jerk Supinator jerk Knee jerk Ankle jerk

Right

Left

SUPERFICIAL REFLEXES

Corneal reflex:

Abdominal reflex:

Cremasteric reflex:

Plantar reflex:

SENSORY SYSTEM

1. Proprioception2. Exterioception3. Cortical

a. Pain sensation: by Semmes –Weinstein monofilament test.

Left Foot Monofilament Test Right Foot

b. Vibration sensation: By 128Hz tuning fork

Left Foot Vibration Perception Right Foot

Autonomic function:

CARDIOVASCULAR SYSTEM

Positive findings:

RESPIRATORY SYSTEM

Positive findings:

PROVISIONAL DIAGNOSIS

Investigations:

Fasting blood glucose Postprandial blood glucose Blood routine Urine routine Urine culture and sensitivity Blood urea Serum creatinine ESR Microalbuminuria detection by albumin creatinine ratio estimation