Describe a glucose tolerance test.

• A. Fast for 2 hours, baseline measured once
• B. Fast for 6 hours, measure baseline and every hour
• C. Fast for 8-12 hours, baseline glucose level and every 30 minutes for 2 hours
• D. No fasting; measure glucose after a meal

Answer: (C)

A glucose tolerance test measures how the body handles a glucose load over time. The test starts with a long fasting period (typically 8–12 hours) to establish a true baseline blood glucose. After you drink a fixed amount of glucose, glucose levels are checked at set intervals to see how quickly the body processes the sugar and returns to normal. Measuring baseline and then every 30 minutes for about two hours provides the pattern of rise and clearance needed to evaluate insulin response and glucose tolerance.

That sequence matches the described protocol: a prolonged fast, an initial baseline measurement, and subsequent measurements every 30 minutes for two hours. The other options skip the required glucose challenge, use an insufficient fasting period, or rely on measurements after a meal instead of a standardized glucose load.