What is eAG? Estimated Average Glucose

Executive Summary

eAG (average estimated glucose ) is a calculated value that translates your A1C percentage into the same units (mg/dL or mmol/L) used on your home glucose meter. It helps patients understand their 3-month average in the context of their daily finger-stick readings.

Why do we use eAG?

For years, patients were confused by A1C results. A doctor might say, "Your A1C is 7%," but the patient's meter says "154." To bridge this gap, the American Diabetes Association (ADA) and other organizations created the eAG metric.

It allows you to compare your "big picture" lab result directly with your daily snapshots.

The Mathematical Relationship

The relationship between A1C and eAG was established by the ADAG (A1C-Derived Average Glucose) study, which monitored hundreds of people using continuous glucose monitors (CGM) and compared their actual average glucose to their A1C.

A1C (%)	eAG (mg/dL)	eAG (mmol/L)
6.0%	126	7.0
7.0%	154	8.6
8.0%	183	10.2
9.0%	212	11.8
10.0%	240	13.4

Is eAG the same as my meter average?

Not necessarily. Many patients find that their meter average (the "14-day average" on the screen) is different from the eAG on their lab report. There are three main reasons for this:

Timing: Your meter only knows your sugar when you prick your finger (usually before or after meals). It doesn't know your sugar while you sleep or in between tests.
Frequency: If you only test when you feel "high," your meter average will be higher than your actual eAG.
Glycation Speed: Some people's bodies naturally "sugar-coat" hemoglobin faster than others, which can cause a slight mismatch between blood glucose and A1C.

Benefits of Tracking eAG

Goal Setting: It's easier to aim for a daily average of "150 mg/dL" than a percentage of "6.8%."
Pattern Recognition: If your eAG is much higher than your meter average, it's a sign that you are spiking at times when you aren't testing (such as overnight).

Clinical Note

If you use a CGM, you might see a number called GMI (Glucose Management Indicator). While similar to eAG, GMI is calculated differently and is often more accurate for CGM users.

Calculate Your eAG Now

Want to know exactly what your latest A1C means in mg/dL or mmol/L? Use our specialized converter.

Go to eAG Calculator →

Frequently Asked Questions

What formula is used for eAG?

The formula is: eAG (mg/dL) = (28.7 × A1C) - 46.7. For mmol/L, the result is divided by 18.018.

Why is eAG sometimes called "eA1C"?

"eA1C" is a confusing term that some apps use. It usually means an "estimated A1C" based on glucose. eAG is the official medical term for "estimated glucose" based on A1C.

Is eAG used for Type 1 and Type 2?

Yes. The ADAG study included patients with Type 1 and Type 2 diabetes, as well as people without diabetes, making the eAG calculation valid for almost everyone.

The Biochemistry of Glycated Hemoglobin

To understand A1C, we must look at the Amadori rearrangement. This is a series of chemical reactions where glucose bonds to the N-terminal valine of the hemoglobin beta chain. Because this bond is nearly irreversible, the percentage of glycated hemoglobin remains stable throughout the 120-day lifespan of the erythrocyte. This makes A1C a superior metric for long-term glycemic control compared to transient plasma glucose tests.

References

Diabetes Care - Translating the A1C Assay into eAG
[ADA - eAG (average estimated glucose ) FAQ](https://diabetes.org/diabetes/a1c/estimated-average-glucose)
NIDDK - Diabetes Test Results

Learn more in our comprehensive What is A1C? complete guide.