Diabetes Education Certification Diabetes Pathophysiology & Types 3 — Questions and Answers
Question 1: Which hormone secreted by alpha cells DIRECTLY opposes insulin action and is abnormally elevated in both Type 1 and Type 2 diabetes?
- Somatostatin
- Glucagon (Correct answer)
- Amylin
- GLP-1
Correct answer: Glucagon
Glucagon secreted by pancreatic alpha cells stimulates hepatic glucose production and is inappropriately elevated in both types of diabetes, worsening hyperglycemia.
Question 2: The 'incretin effect' is significantly reduced in Type 2 diabetes. Which incretins are primarily involved?
- GLP-1 and GIP (Correct answer)
- GLP-1 and glucagon
- GIP and amylin
- Amylin and somatostatin
Correct answer: GLP-1 and GIP
GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide) are the two main incretins whose reduced effect contributes to impaired postprandial insulin secretion in Type 2 diabetes.
Question 3: Ketosis in Type 1 diabetes occurs primarily because:
- Excess glucose is converted to ketone bodies in the liver
- Absence of insulin disinhibits lipolysis, flooding the liver with free fatty acids (Correct answer)
- Glucagon directly stimulates ketone synthesis independent of insulin
- Renal threshold for glucose is exceeded
Correct answer: Absence of insulin disinhibits lipolysis, flooding the liver with free fatty acids
Without insulin, adipose tissue lipolysis is uninhibited, releasing excessive free fatty acids that the liver converts to ketone bodies (acetoacetate, beta-hydroxybutyrate).
Question 4: Which condition is characterized by severe insulin resistance due to mutations in the insulin receptor gene?
- MODY type 2
- Donohue syndrome (Leprechaunism) (Correct answer)
- Wolfram syndrome
- Alström syndrome
Correct answer: Donohue syndrome (Leprechaunism)
Donohue syndrome (Leprechaunism) is caused by homozygous loss-of-function mutations in the insulin receptor gene (INSR), resulting in extreme insulin resistance from birth.
Question 5: The GLUT4 glucose transporter is unique compared to other glucose transporters because it:
- Is expressed only in the liver and kidneys
- Requires insulin signaling to translocate to the cell membrane (Correct answer)
- Has the highest affinity for glucose of all GLUT transporters
- Is constitutively active regardless of metabolic state
Correct answer: Requires insulin signaling to translocate to the cell membrane
GLUT4 is insulin-responsive; insulin signaling causes GLUT4 vesicles to translocate from intracellular pools to the plasma membrane, enabling glucose uptake in muscle and adipose tissue.
Question 6: Diabetes caused by chronic pancreatitis or pancreatectomy is classified as:
- Type 1 diabetes
- Type 2 diabetes
- Diabetes of the exocrine pancreas (Type 3c) (Correct answer)
- Secondary diabetes
Correct answer: Diabetes of the exocrine pancreas (Type 3c)
Diabetes resulting from diseases of the exocrine pancreas (including chronic pancreatitis, cystic fibrosis, and pancreatectomy) is classified as Type 3c or pancreatogenic diabetes.
Question 7: In prediabetes, which metabolic abnormality is MOST predictive of progression to Type 2 diabetes?
- Impaired fasting glucose alone
- Isolated postprandial hyperglycemia
- Combined impaired fasting glucose and impaired glucose tolerance (Correct answer)
- Elevated HbA1c of 5.6%
Correct answer: Combined impaired fasting glucose and impaired glucose tolerance
The combination of impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) carries the highest risk of progression to Type 2 diabetes compared to either condition alone.
Diabetes Education Certification Diabetes Pathophysiology & Types 3
Which hormone secreted by alpha cells DIRECTLY opposes insulin action and is abnormally elevated in both Type 1 and Type 2 diabetes?