Endocrine Weight Loss Insulin Resistance and Weight Management 1 — Questions and Answers
Question 1: Which tissue is the primary site of insulin-mediated glucose uptake in the postprandial state?
- Liver
- Brain
- Skeletal muscle (Correct answer)
- Adipose tissue
Correct answer: Skeletal muscle
Skeletal muscle accounts for approximately 75–80% of insulin-stimulated glucose disposal after a meal due to its large mass and GLUT4-mediated uptake.
Question 2: Visceral adiposity promotes insulin resistance primarily through which mechanism?
- Increased adiponectin secretion
- Elevated release of free fatty acids and pro-inflammatory cytokines into portal circulation (Correct answer)
- Decreased cortisol receptor sensitivity
- Enhanced GLUT4 expression in muscle
Correct answer: Elevated release of free fatty acids and pro-inflammatory cytokines into portal circulation
Visceral fat drains via the portal vein, delivering excess free fatty acids and inflammatory cytokines (TNF-α, IL-6) directly to the liver, impairing insulin signaling.
Question 3: The HOMA-IR (Homeostatic Model Assessment of Insulin Resistance) is calculated using:
- Fasting glucose × fasting insulin ÷ 22.5 (Correct answer)
- Post-load glucose × HbA1c ÷ 10
- Fasting C-peptide × BMI ÷ 25
- 2-hour glucose × fasting insulin ÷ 405
Correct answer: Fasting glucose × fasting insulin ÷ 22.5
HOMA-IR = (fasting glucose in mmol/L × fasting insulin in mIU/L) ÷ 22.5; higher values indicate greater insulin resistance.
Question 4: Which dyslipidemia pattern is most characteristically associated with insulin resistance?
- Elevated HDL, elevated LDL, normal triglycerides
- Low HDL, elevated triglycerides, and small dense LDL particles (Correct answer)
- Isolated elevated LDL with normal triglycerides
- Elevated HDL, low LDL, normal triglycerides
Correct answer: Low HDL, elevated triglycerides, and small dense LDL particles
Insulin resistance drives overproduction of VLDL, resulting in hypertriglyceridemia, low HDL, and a predominance of small, dense LDL particles—the atherogenic dyslipidemia triad.
Question 5: Metformin promotes weight-neutral or mild weight loss in insulin-resistant patients primarily through which mechanism?
- Stimulating leptin secretion from adipocytes
- Reducing hepatic glucose output and improving insulin sensitivity without hypoglycemia (Correct answer)
- Blocking intestinal fat absorption via lipase inhibition
- Increasing brown adipose thermogenesis
Correct answer: Reducing hepatic glucose output and improving insulin sensitivity without hypoglycemia
Metformin primarily suppresses hepatic gluconeogenesis via AMPK activation, reduces hyperinsulinemia, and may mildly reduce appetite, contributing to weight neutrality or modest loss.
Question 6: Which of the following best describes the 'carbohydrate-insulin model' of obesity?
- Dietary fat is the primary driver of obesity regardless of carbohydrate intake
- High glycemic carbohydrates raise insulin, which promotes fat storage and reduces fat availability for fuel (Correct answer)
- Protein intake directly determines insulin secretion and fat mass
- Calories from all macronutrients are equally fattening irrespective of hormonal response
Correct answer: High glycemic carbohydrates raise insulin, which promotes fat storage and reduces fat availability for fuel
The carbohydrate-insulin model proposes that high glycemic index foods drive insulin secretion, promoting fat storage and reducing fat availability as fuel, thereby increasing hunger and fat accumulation.
Endocrine Weight Loss Insulin Resistance and Weight Management 1
Which tissue is the primary site of insulin-mediated glucose uptake in the postprandial state?