An HbA1c of 6.5% or higher is diagnostic for which condition?

• A. Diabetes
• B. Prediabetes
• C. Normal glucose tolerance
• D. Gestational diabetes

Answer: (A)

HbA1c measures average blood glucose over the past 2–3 months. When the value reaches 6.5% or higher, it meets the diagnostic threshold for diabetes because it reflects sustained hyperglycemia rather than temporary fluctuations.

Prediabetes falls in the 5.7%–6.4% range, and normal glucose tolerance is below 5.7%. Gestational diabetes isn’t diagnosed by HbA1c; it’s determined with pregnancy-specific glucose testing, such as an oral glucose tolerance test, since pregnancy changes glucose dynamics and standard HbA1c thresholds aren’t used there. In practice, confirming diabetes usually involves repeating the abnormal result on a separate day, but the 6.5% cutoff is the key point identifying diabetes.