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HbA1c ↔ eAG Converter
eAG (mg/dL) = 28.7 × HbA1c − 46.7 — the standard ADA conversion formula. Goal range for diabetes management: HbA1c < 7%, eAG < 154 mg/dL.
Target: < 7% / < 154 mg/dL for most diabetics. Discuss with your doctor.
What HbA1c measures
HbA1c is the percentage of haemoglobin molecules that have glucose attached. Because red blood cells live ~120 days, HbA1c gives the 3-month average glucose exposure — far more reliable than a single fasting reading that swings with last night's dinner. The Nathan formula eAG (mg/dL) = 28.7 × HbA1c − 46.7 converts the % into the everyday glucose meter units.
Worked example
A patient on metformin scores HbA1c 7.5%. eAG = 28.7 × 7.5 − 46.7 = 168 mg/dL — meaning the daily average is well above the 154 mg/dL target. After 3 months of diet change (low GL meals, 8000 steps/day) HbA1c drops to 6.4% → eAG ~137 mg/dL — back in pre-diabetic range. Each 1% HbA1c drop reduces microvascular complications by ~37% (UKPDS data).
Indian thresholds (ICMR + ADA)
- HbA1c < 5.7% (eAG < 117) — normal
- 5.7–6.4% (eAG 117–137) — pre-diabetic, lifestyle intervention urgent
- ≥ 6.5% (eAG ≥ 140) — diabetic by WHO/ADA criteria
- < 7% — treatment goal for most adult diabetics
- < 6.5% — tighter goal for young, no-complications
Pair this with the Indian Diabetes Risk Score for screening, and the glycemic load calculator for meal planning.
FAQ
What HbA1c is normal vs diabetic?
Normal: < 5.7%. Pre-diabetic: 5.7-6.4%. Diabetic: ≥ 6.5%. The 5.7-6.4% window is the reversible range — diet + exercise can move you back down.
How often should diabetics test HbA1c?
Every 3 months if recently diagnosed or unstable. Every 6 months once stable on medication. The 3-month frequency exists because HbA1c reflects the past ~90 days.
Is fingerprick HbA1c accurate?
Less than venous lab. Point-of-care machines (DCA Vantage etc.) can have ±0.5% variance. For diagnosis or treatment decisions, use a venous sample at a NABL-accredited lab.