OGT Medications and Factors Affecting OGTT Results 2 — Questions and Answers
Question 1: Acute physiological stress such as surgery or serious infection affects OGTT reliability by:
- Having no effect on glucose levels
- Lowering glucose through increased metabolic rate
- Raising glucose via counter-regulatory hormone release (Correct answer)
- Improving insulin sensitivity temporarily
Correct answer: Raising glucose via counter-regulatory hormone release
Stress triggers release of cortisol, epinephrine, glucagon, and growth hormone, all of which raise blood glucose — making OGTT during acute illness invalid.
Question 2: Which endocrine condition, if untreated, will predictably cause abnormal OGTT results due to excess growth hormone?
- Hypothyroidism
- Cushing's syndrome
- Acromegaly (Correct answer)
- Addison's disease
Correct answer: Acromegaly
Acromegaly (excess growth hormone) causes insulin resistance and impaired glucose tolerance, commonly revealed by OGTT.
Question 3: Hyperthyroidism affects OGTT interpretation because thyroid hormones:
- Slow intestinal glucose absorption
- Accelerate glucose absorption and increase hepatic glucose output, elevating post-load glucose (Correct answer)
- Improve beta-cell function
- Lower fasting glucose by stimulating glycogenesis
Correct answer: Accelerate glucose absorption and increase hepatic glucose output, elevating post-load glucose
Excess thyroid hormones accelerate gastrointestinal glucose absorption and increase hepatic glucose output, causing an exaggerated early OGTT peak.
Question 4: Which factor associated with prolonged bed rest most significantly impairs OGTT results?
- Muscle atrophy increasing glucose disposal
- Increased GLP-1 secretion
- Skeletal muscle insulin resistance from physical inactivity (Correct answer)
- Reduced hepatic glucose output
Correct answer: Skeletal muscle insulin resistance from physical inactivity
Physical inactivity from bed rest reduces GLUT4 expression and decreases insulin-stimulated glucose uptake in skeletal muscle, worsening insulin sensitivity.
Question 5: Alcohol consumption the night before an OGTT can cause:
- No change in results
- Falsely low fasting glucose due to inhibition of hepatic gluconeogenesis (Correct answer)
- Falsely high 2-hour glucose
- Increased insulin secretion
Correct answer: Falsely low fasting glucose due to inhibition of hepatic gluconeogenesis
Alcohol inhibits hepatic gluconeogenesis, which can cause falsely low fasting glucose on an OGTT performed the morning after drinking.
Question 6: Caffeine consumption before an OGTT has been shown to:
- Have no effect on glucose levels
- Lower post-load glucose through insulin mimicry
- Impair insulin sensitivity and raise post-load glucose (Correct answer)
- Accelerate gastric emptying only
Correct answer: Impair insulin sensitivity and raise post-load glucose
Caffeine reduces insulin sensitivity and can raise post-load plasma glucose by up to 30%, potentially confounding OGTT results.
OGT Medications and Factors Affecting OGTT Results 2
Acute physiological stress such as surgery or serious infection affects OGTT reliability by: