CHAPTER 33DIABETES MELLITUS AND THE METABOLIC SYNDROME
Essentials of Pathophysiology
PRE LECTURE QUIZ Type 2 diabetes is more common than type 1. All cells can use fatty acids interchangeably
with glucose for energy. Insulin is produced by the pancreatic beta
cells in the islets of Langerhans. Hyperglycemia is characterized by headache,
difficulty in problem solving, disturbed or altered behavior, coma, and seizures.
Chronic complications of diabetes mellitus refer only to type 1 diabetes mellitus.
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F
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PRE LECTURE QUIZ ______________ lowers the blood glucose
concentration by facilitating the movement of glucose into body tissues.
Glucagon, a polypeptide molecule produced by the _____________ cells of the islets of Langerhans, maintains blood glucose between meals and during periods of fasting.
Type __________ diabetes mellitus is characterized by destruction of the pancreatic beta cells and is characterized by an absolute lack of insulin, an elevation in blood glucose, and a breakdown of body fats and protein.
The ________________ syndrome is a condition of abnormalities that are identified through specific criteria such as abdominal obesity, elevated triglycerides, elevated blood pressure, elevated fasting plasma glucose, and decreased high-density lipoprotein cholesterol (HDL).
Diabetic ____________________ occurs when ketone production by the liver exceeds cellular use and renal excretion.
Alpha
Insulin
ketoacidosis
Metabolic
one
ANABOLISM AND CATABOLISM
Anabolisminsulin, anabolic steroids
Catabolismglucagon,
epinephrine, cortisol
available foodstuffs (in blood)
glucose
amino acids
free fatty acids
stored foodstuffs (in cells)
glycogen
proteins
triglycerides
liver can convert amino acids and free fatty acids into
ketones
INSULIN AND GLUCAGON ARE THE MAIN CONTROLS
Anabolisminsulin , anabolic steroids
Catabolismglucagon , epinephrine,
cortisol
available foodstuffs (in blood)
glucose
amino acids
free fatty acids
stored foodstuffs (in cells)
glycogen
proteins
triglycerides
liver can convert amino acids and free fatty acids into
ketones
QUESTION
Tell whether the following statement is true or false.
Anabolic reactions release energy.
ANSWER
FalseRationale: Anabolic reactions use
energy to build/produce/synthesize (like building proteins from amino acids). Catabolic reactions break down substances, releasing energy in the process (like digestion).
SCENARIO
Two women have benign pancreatic tumors. In one, the tumor is an insulinoma that secretes
insulin In the other, the tumor is a glucagonoma that
secretes glucagonQuestions: What differences do you expect to see between
these two women? Why? Both of the women have arthritis, but only one is
being treated with corticosteroids. Which one? Why is the other not receiving corticosteroids?
THE PANCREAS
pancreas
exocrine pancreas
releases digestive juices through a
duct
to the duodenum
endocrine pancreas
releases hormones into the blood
endocrine pancreas: islets of
Langerhans
alpha cells beta cells delta cells PP cells
pancreatic polypeptide glucagon
insulinand amylin somatostatin
FUNCTIONS OF PANCREATIC HORMONES
Glucagon: causes cells to release stored food into the blood
Insulin: allows cells to take up glucose from the blood
Amylin: slows glucose absorption in small intestine; suppresses glucagon secretion
Somatostatin: decreases GI activity; suppresses glucagon and insulin secretion
QUESTION
Which pancreatic hormone decreases blood glucose levels?
a. Glucagonb. Insulinc. Amylind. Somatostatin
ANSWER
b. InsulinRationale: Insulin allows cells to take
glucose from the blood and use it for energy/to make ATP. Because it stimulates movement of glucose out of the blood and into the cells, blood glucose levels decrease when insulin is released.
DISCUSSIONThink back on your day so far. When do you think you had your
highest insulin levels? When do you think you had your
lowest insulin levels? When did you have your highest
glucagon levels?
DISCUSSION
Review the figure on insulin’s actions. If someone lacks insulin, what
happens to his: Blood glucose levels? Blood amino acid levels? Blood pH? Intracellular fat levels? Intracellular protein levels? Cell growth?
DISCUSSION
Review the following diagrams on anabolism/catabolism and insulin’s mechanism of action.
Questions: Identify five things that could go wrong to cause
increased blood glucose Which of the cases you identified would be least
likely to respond to insulin?
ANABOLISM AND CATABOLISM
Anabolisminsulin, anabolic steroids
Catabolismglucagon,
epinephrine, cortisol
available foodstuffs (in blood)
glucose
amino acids
free fatty acids
stored foodstuffs (in cells)
glycogen
proteins
triglycerides
liver can convert amino acids and free fatty acids into
ketones
TYPES OF DIABETES MELLITUS Type 1: pancreatic beta cell
destruction predominantly by an autoimmune process
Type 2: a combination of beta cell dysfunction and insulin resistance
Other Genetic defects in insulin production Genetic defects in insulin action Diabetes secondary to other diseases Drug interactions
Gestational diabetes mellitus
PATHOGENESIS OF TYPE 2 DIABETES
QUESTION
Tell whether the following statement is true or false.
Type 2 DM is more common than type 1 DM.
ANSWER
TrueRationale: Type 1 DM is autoimmune
(juvenile diabetes is type 1), and affects only 5–10% of the diabetic population. Type 2 DM is associated with risk factors like obesity, poor diet, and sedentary lifestyle; 90–95% of diabetics suffer from this type.
METABOLIC SYNDROME Abdominal obesity Increased blood triglyceride
levels Decreased HDL levels Increased blood pressure Increased fasting plasma
glucose
TREATMENTS FOR TYPE 2 DIABETES
ACUTE COMPLICATIONS OF DIABETES
Diabetic ketoacidosis Hyperglycemic hyperosmolar nonketotic
coma Hypoglycemia Somogyi effect Dawn phenomenon
ACUTE COMPLICATIONS OF DIABETES (CONT.)
Discussion How would hyperglycemia with ketoacidosis
cause: Heavy breathing? Polyuria? Dehydration?
Which of these would you not see in hyperglycemia without ketoacidosis?
SCENARIO
You find a man collapsed on the sidewalk. He is wearing a diabetic alert bracelet and
has an insulin syringe in his briefcaseQuestions: Does he need insulin? Why or why not? What signs might help you tell whether he
has a hyperglycemic or hypoglycemic problem?
CHRONIC COMPLICATIONS OF DIABETES MELLITUS Increased glucose levels allow
glucose to bind to proteins in: Hemoglobin Hb A1C has higher O2
affinity Basement membranes of blood vessels
º Nephropathyº Retinopathy º May cause increased risk of atherosclerosis
Lens cataracts(Porth, C. M. [2005]. Pathophysiology [7th ed.]. Lippincott Williams & Wilkins andGreenspan, F. & Gardner, D. G. [2004]. Basic and clinical endocrinology [7th ed.]. McGraw-Hill.)
OSMOLARITY IN DIABETES MELLITUS
When blood glucose is high, increased blood osmolarity can cause cells to shrink
Nerve cells produce intracellular osmoles to keep their osmolarity balanced with the blood
A
B
Hypotonic cell A shrinks
Cell B is in osmotic balance
(Porth, C. M. [2005]. Pathophysiology [7th ed.]. Lippincott Williams & Wilkins.)
OSMOLARITY IN DIABETES MELLITUS (CONT.)
When the client brings blood glucose back to normal, the nerve cells are hyperosmolar to the blood and gain water, swelling
Nerve damage may be caused by swelling, demyelination, and lack of O2 secondary to vascular disease
A
B
Cell A is in osmotic balance
Hypertoniccell B swells
(Porth, C. M. [2005]. Pathophysiology [7th ed.]. Lippincott Williams & Wilkins.)
DIABETIC NEUROPATHY
Somatic neuropathy Diminished perception of vibration, pain,
and temperature Hypersensitivity to light touch; occasionally,
severe “burning” pain Autonomic neuropathy
Defects in vasomotor and cardiac responses Impaired motility of the gastrointestinal
tract Inability to empty the bladder Sexual dysfunction
QUESTION
Which of the following is not a complication of diabetes mellitus?
a. Nephropathyb. Retinopathyc. Neuropathyd. All of the above are complications of
DM.
ANSWER
d. All of the above are complications of DM.
Rationale: Nephropathy and retinopathy are caused by increased blood glucose levels that cause binding of excess glucose to the basement membranes of the blood vessels of the kidneys and eyes. Neuropathy is due to swelling and demyelination of nervous tissue.
DIABETIC FOOT ULCERTypical Diabetic Foot Ulcer Advanced Diabetic Foot Ulcer