Hemoglobin A1c

Definition

Hemoglobin A1c (HbA1c) reflects average blood glucose over a 2- to 3-month period.

How it works

Glucose irreversibly binds to hemoglobin (glycation). Higher average 3-month glucose, higher HbA1c. Values: <5.7% normal, 5.7-6.4% prediabetes, ≥6.5% diabetes. Therapeutic goal is generally <7% to limit complications.

Role

Evaluate long-term glycemic control and diabetes complication risk.

Examples

• HbA1c 8% ≈ average glucose 1.83 g/L. Reducing 1% → -30% microvascular complication risk.

Recommendations

Measure every 3-6 months in diabetics. Recommended screening after 45 years or with risk factors.

Key takeaway

HbA1c is more reliable than spot glucose due to 3-month glycemic reflection.

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