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4%14%
mg/dL
154
US Standard
mmol/L
8.6
International
Target Range
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About

Hemoglobin A1c (HbA1c) reflects the average blood glucose levels over the preceding two to three months. However, daily monitoring usually occurs in mg/dL or mmol/L. The estimated Average Glucose (eAG) metric bridges this gap, translating the A1c percentage into the same units used by standard glucometers. This correlation helps patients and clinicians understand how long-term trends align with daily readings. The conversion is based on the ADAG (A1c-Derived Average Glucose) study, which established the linear relationship between A1c and mean glucose concentrations.

diabetes A1c blood glucose eAG medical calculator

Formulas

The ADAG study established the following linear regression equation to convert HbA1c to estimated Average Glucose (eAG):

eAGmg/dL = (28.7 × A1c) 46.7

For international units (mmol/L), the conversion is derived from the molecular weight of glucose:

eAGmmol/L = (1.59 × A1c) 2.59

Reference Data

HbA1c (%)eAG (mg/dL)eAG (mmol/L)Control Level
5.0975.4Normal
5.51116.2Normal
6.01267.0Pre-diabetes
6.51407.8Diabetes Diagnosis
7.01548.6Target (Adults)
8.018310.2Elevated
9.021211.8High
10.024013.4Very High
11.026914.9Critical
12.029816.5Critical

Frequently Asked Questions

Standard glucometers often capture fasting or pre-meal levels, missing post-prandial spikes or nocturnal lows. HbA1c represents a continuous 24-hour average over months. Consequently, the eAG calculated from A1c might be higher than the average of sporadic meter checks.
No. Fasting glucose measures blood sugar after 8+ hours without food. eAG is an average that includes fasting periods, post-meal spikes, and sleep levels. eAG is typically higher than fasting glucose in diabetic patients.
Red blood cells have a lifespan of approximately 120 days. Therefore, A1c changes relatively slowly. It takes about 2 to 3 months for the A1c percentage to fully reflect a change in treatment or diet.