Which test is used mainly for monitoring long-term glycemic control?

• A. FBS
• B. HbA1c
• C. 1,5-AG
• D. Fructosamine

Answer: (B)

HbA1c is used for monitoring long-term glycemic control because it measures the fraction of hemoglobin that has glucose attached, which accumulates as red blood cells circulate. Since red blood cells live about 120 days, HbA1c reflects average blood glucose over roughly 2–3 months, smoothing out daily fluctuations and the effects of a single meal or temporary stress. This makes it the best indicator for chronic glycemic control and for assessing how well therapy is working over time. In contrast, fasting glucose provides a snapshot of glucose at one moment, 1,5-anhydroglucitol tracks short-term fluctuations over days to weeks, and fructosamine reflects glycation over about 2–3 weeks. Note that conditions altering red blood cell turnover can affect HbA1c accuracy.