HbA1c is reported as a percentage — a number that is clinically meaningful but abstract for many people. Estimated average glucose (eAG) translates A1c into the same blood glucose units seen on a home meter, making the result more intuitive for daily diabetes management discussions.
Why eAG was introduced
The ADA introduced eAG reporting to help bridge the gap between the A1c percentage that clinicians monitor and the mmol/L or mg/dL values that people with diabetes see on their meters every day. An A1c of 7% corresponds to an eAG of approximately 8.6 mmol/L (154 mg/dL) — a value that feels concrete when compared against meter readings.
The ADAG (A1c-Derived Average Glucose) study validated this formula using continuous glucose monitoring data across a racially diverse population with and without diabetes. The resulting linear formula provides a reasonable estimate for most individuals, though individual variation of up to ±0.5–1.5 mmol/L (10–30 mg/dL) is documented.
Worked example: converting a lab HbA1c
If a lab report shows an HbA1c of 7.0%, the ADAG formula converts that to an estimated average glucose of about 8.6 mmol/L or 154 mg/dL. That helps explain how fasting readings in the 6-7 mmol/L range can still fit an overall average that is higher once post-meal rises and overnight values are included.
eAG versus daily readings
eAG represents an average across all times of day, including post-meal peaks. It will therefore typically be higher than a pre-breakfast fasting reading on a home meter. A person with an A1c of 7% (eAG 8.6 mmol/L) might see fasting readings of 6–7 mmol/L and post-meal readings of 9–11 mmol/L, both consistent with that average.
Frequently asked questions
Is eAG the same as average glucose on a CGM?
Not exactly. CGM average glucose is a direct measurement average from hundreds of readings per day. eAG is a formula estimate derived from A1c. Both reflect average glucose over a similar period, but they are calculated differently and typically agree within 1–2 mmol/L. CGM average glucose is generally more precise for individuals because it is measured rather than estimated.
Why does my eAG seem higher than my typical meter readings?
Home meters are typically used for fasting or specific test times (before meals, before bed). eAG includes the post-meal peaks that make up a large proportion of daily glucose time, which most people do not routinely measure. The average including those peaks is typically higher than fasting-focused self-monitoring suggests.
What can change the estimated average glucose calculator result?
The estimated average glucose calculator result can change when the inputs, the planning assumptions, or the measurement context change. That is why the page is most useful when you read the result alongside the method notes, limitations, and any caution states rather than treating one output as a complete medical or nutrition answer.
