Estimated Average Glucose (eAG)

What This Calculator Measures

Estimates mean plasma glucose from HbA1c using the ADAG equation, translating A1c into a mg/dL value patients can compare with home glucose readings.

How to Use

1. Enter the NGSP-standardized HbA1c value (%).
2. Review the estimated average glucose in mg/dL.
3. Interpret against the normal range of 70–140 mg/dL and the ADA target of eAG ≈154 mg/dL.

Interpretation Guide

eAG ≤140 mg/dL is normal, eAG above 140 up to 200 mg/dL is the pre-diabetic range, and eAG >200 mg/dL is in the diabetic range. eAG reflects average glucose over the preceding 2–3 months.

Clinical Significance

eAG converts A1c into a practical mg/dL value, improving patient comprehension and facilitating shared decision-making about glycemic control.

When to Use

• Translating A1c into familiar glucose units for patient education
• Assessing overall glycemic control over 2–3 months
• Setting and reviewing glycemic targets

When Not to Use

• In conditions altering red cell lifespan (iron deficiency, sickle cell trait, pregnancy)
• As a substitute for CGM or self-monitoring data when variability is the question

Limitations

• Derived from continuous glucose monitoring studies and may differ from finger-stick averages.
• Does not reflect glucose variability or hypoglycemic episodes.
• Affected by conditions that change red blood cell survival.

Worked Example

A 60-year-old patient with impaired glucose tolerance has an HbA1c of 6.0%.

eAG = 28.7 × 6.0 − 46.7 = 125.5 mg/dL — normal average glucose range.

Evidence

Source

ADA / ADAG Study

Reference

Nathan DM, et al. Diabetes Care. 2008;31(8):1473-1478.

Reviewed By

MedCalcHub Clinical Team

Version

2008

1. Nathan DM, et al. Diabetes Care. 2008;31(8):1473-1478.

References

1. Nathan DM, Kuenen J, Borg R, et al. Translating the A1c assay into estimated average glucose values. Diabetes Care. 2008;31(8):1473-1478. (Primary Study)

Frequently Asked Questions