BC ADM Fundamentals & Core Concepts 4 — Questions and Answers
Question 1: The term 'incretin effect' describes which physiological phenomenon?
- Greater insulin secretion after oral glucose compared to an equivalent IV glucose load (Correct answer)
- Suppression of glucagon by somatostatin in the islet
- Enhanced peripheral glucose uptake mediated by GLP-1 receptors in muscle
- Delayed gastric emptying caused by high-fat meals
Correct answer: Greater insulin secretion after oral glucose compared to an equivalent IV glucose load
The incretin effect refers to the amplified insulin secretion seen with oral vs. intravenous glucose due to gut-derived hormones GLP-1 and GIP.
Question 2: In maturity-onset diabetes of the young (MODY), which gene mutation causes MODY 2, the mildest form?
- HNF-1α (TCF1)
- HNF-4α (HNF4A)
- Glucokinase (GCK) (Correct answer)
- PDX1
Correct answer: Glucokinase (GCK)
MODY 2 is caused by glucokinase (GCK) mutations, resulting in a higher glucose threshold for insulin secretion and mild, stable fasting hyperglycemia.
Question 3: Hyperglycemia causes endothelial dysfunction primarily through which mechanism?
- Direct inhibition of endothelial nitric oxide synthase (eNOS) gene transcription
- Increased reactive oxygen species production that quenches nitric oxide (Correct answer)
- Elevated LDL receptor expression on endothelial cells
- Reduced angiotensin-converting enzyme activity
Correct answer: Increased reactive oxygen species production that quenches nitric oxide
Excess glucose increases mitochondrial superoxide production, which quenches nitric oxide, impairing vasodilation and promoting endothelial dysfunction.
Question 4: Which of the following best defines 'brittle diabetes'?
- Type 2 diabetes requiring more than 200 units of insulin per day
- Type 1 diabetes with recurrent unpredictable severe hypoglycemia or ketoacidosis disrupting daily life (Correct answer)
- Any diabetes with HbA1c persistently above 10% despite therapy
- Diabetes associated with pancreatic exocrine insufficiency
Correct answer: Type 1 diabetes with recurrent unpredictable severe hypoglycemia or ketoacidosis disrupting daily life
Brittle diabetes refers to type 1 diabetes with extreme glycemic instability causing frequent severe episodes that substantially disrupt the patient's life.
Question 5: The polyol pathway contributes to diabetic complications by:
- Directly glycating structural proteins in vessel walls
- Consuming NADPH and depleting glutathione, increasing oxidative stress (Correct answer)
- Activating protein kinase C via diacylglycerol
- Producing advanced glycation end-products (AGEs)
Correct answer: Consuming NADPH and depleting glutathione, increasing oxidative stress
The polyol pathway uses NADPH to reduce glucose to sorbitol, depleting glutathione antioxidant capacity and increasing cellular oxidative stress in diabetic tissues.
Question 6: A random plasma glucose ≥ 200 mg/dL with classic symptoms of hyperglycemia is diagnostic of diabetes:
- Only if confirmed by a second test on a different day
- Only in the absence of acute illness or stress
- Without the need for confirmatory testing (Correct answer)
- Only when accompanied by HbA1c ≥ 6.5%
Correct answer: Without the need for confirmatory testing
Per ADA criteria, a random plasma glucose ≥ 200 mg/dL with classic hyperglycemia symptoms (polyuria, polydipsia, unexplained weight loss) is sufficient to diagnose diabetes.
Question 7: Which hormone secreted by alpha cells of the pancreas is the primary counterregulatory hormone during hypoglycemia?
- Somatostatin
- Amylin
- Glucagon (Correct answer)
- Pancreatic polypeptide
Correct answer: Glucagon
Glucagon, secreted by pancreatic alpha cells, is the first-line counterregulatory hormone, stimulating hepatic glycogenolysis and gluconeogenesis to restore glucose.
BC ADM Fundamentals & Core Concepts 4
The term 'incretin effect' describes which physiological phenomenon?