Which marker measures very short glycemic control over about 1-2 weeks?

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

Answer: (C)

Very short-term glycemic control is best assessed by markers that respond quickly to recent glucose exposure, especially spikes after meals. 1,5-anhydroglucitol fits this because its serum level stays relatively stable under normal glycemia, but when blood glucose exceeds the kidney’s reabsorptive capacity, glucose is excreted in the urine and competes with 1,5-anhydroglucitol for reabsorption. This competition causes 1,5-anhydroglucitol to fall rapidly, and its level reflects glycemic status over roughly the past 1 to 2 weeks. So it acts as a sensitive gauge of recent glycemic excursions.

In contrast, fasting blood sugar is just a single time-point measurement and can be influenced by short-term factors. HbA1c shows average glucose over about 2–3 months, smoothing out short-term fluctuations. Fructosamine reflects glycation of serum proteins over about 2–3 weeks—closer to short-term than HbA1c but not as temporally precise as 1,5-anhydroglucitol. Therefore, the marker best capturing very short-term glycemic control over about 1–2 weeks is 1,5-anhydroglucitol.