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Metabolic complications of Diabetes Mellitus

Dr. Essam H. Jiffri

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Introduction

- Metabolic complications, particularly diabetic ketoacidosis and hypoglycaemia,

are life-threatening and can cause permanent neurological damages.

-Diabetic patients present with impaired consciousness may be caused by other conditions

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Diabetic Ketoacidosis

-Diabetic ketoacidosis (DKA) was responsible for 70% of diabetic deaths before the advent of insulin therapy and mortality rates are still up to 7%.

-It is mainly a recognized complication of IDDM, DKA can also occur in NIDDM.

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Diabetic Ketoacidosis

-The clinical features of DKA result from:

– insulin deficiency – increases in counter-regulatory

hormones, produce major changes in:

• fuel, water and electrolyte metabolism

• glycogenolysis and gluconeogenesis occur.

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Diabetic Ketoacidosis

Increased secretion

of counter-regulatory hormones leading to increased hepatic

glucose output

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Diabetic Ketoacidosis

-Tissue uptake of glucose is reduced, contributing to the hyperglycaemia.

-As glucose does not enter cells, the extracellular osmotic pressure tends to rise, causing water to transfer from the intracellular to extracellular compartment.

- The renal threshold for glucose is exceeded and glycosuria occurs.

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Diabetic Ketoacidosis

- The presence of excess non-absorbed solute in the glomerular filtrate causes an osmotic diuresis which interferes with tubular reabsorptive function, leading to:

• water

• sodium and

• potassium depletion

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Diabetic Ketoacidosis

- Lipolysis results from insulin deficiency

- NEFAs are released and transported to liver(reduced insulin and increased glucagon) leading to:• greater amount of fatty acids being

metabolized by beta-oxidation• Acetyl CoA is exceeded and increased

amount of ketone bodies

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Diabetic Ketoacidosis

- Acetoacetate and β-hydroxybutyrate are week acids and increase H+ conc in the blood, exceeding the buffering capacity and causing acidosis

- The H+ ions exchange with potassium across cell membranes, causing hyperkalaemia in some patients.

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Diabetic Ketoacidosis

The effect of acidosis

is direct stimulation

of respiratory centre

by H+, causing deep hyperventilation (Kussmaul breathing)

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Diabetic Ketoacidosis

- A history of polyuria, polydipsia, fatigue and vomiting.

- Physical signs include:• dehydration• tachycardia,• warm skin• Kussmaul respiration• Odour of acetone on the breath

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Diabetic KetoacidosisManagement

- Diabetic ketoacidosis is a medical emergency.

- The aim of treatment is to replace fluids and electrolytes, and restore metabolic control.

- Patients require several liters of isotonic solution of saline to be infused, because of

loss of sodium.

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Diabetic KetoacidosisManagement

-Intravenous insulin infusion is required, initially 6 units h-1.

- Intravenous potassium may be required, the rate depending on the plasma potassium

level.

- Bicarbonate is sometimes infused to correct the metabolic acidosis in severely affected patients (pH 7.0).

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Diabetic KetoacidosisMonitoring

- Blood glucose should be monitoring hourly using test strip.

- Laboratory analysis of glucose and electrolytes should be done after 2h, and four hourly until the patient is stable.

- Blood gases should be monitored periodaclly.

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Hyperosmolar Non-ketotic Coma

- Occurs mainly in elderly patient with NIDDM

- Some degree of ketosis

- Hyperglycaemia is more severe than in DKA

- The condition has a high mortality rate over 50%

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Lactic Acidosis

Lactic acidosis is usually associated with renal failure

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Principal features of three forms of metabolic decompensation in diabetes

Features Diabetic ketoacidosis

Hyperosmolar nonketotic coma (HONK)

lactic acidosois

Plasma glucoseHighVery highVariable

KetosispresentNoneVariable

AcidosisModerate/

Severe

NoneSevere

DehydrationProminentProminentVariable

HyperventilationPresentNonePresent

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Long-term complication

long-term complications may result from :

•Microvascular changes

•Macrovascular disease

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KEY POINTS

Diabetic Ketoacidosis (DKA) is a medical emergency

Patients with DKA are dehydrated, sodium depleted and acidotic

Plasma potassium levels should be monitored during treatment