Why is fasting recommended before glucose testing?

• A. To avoid dehydration during testing
• B. To ensure accurate saline measurement
• C. To improve sample volume
• D. To avoid postprandial hyperglycemia that could mask diabetic conditions; reduces variability

Answer: (D)

Fasting before glucose testing is about getting a stable, baseline measurement. After a meal, blood glucose can spike and then fluctuate widely as digestion and insulin response vary between individuals. Those post-meal changes add a lot of variability and can mask whether someone has consistently elevated glucose levels or diabetes. When you fast, you minimize these fluctuations, so the test result reflects the body's resting glucose control and aligns with diagnostic thresholds defined for a fasting state. This makes the result more accurate and reproducible across patients and tests.