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Estimated average glucose (eAG)
Some labs print an estimated average glucose next to the A1c. It is the same result in the units of a glucose meter, so the two always move together.
The short answer
- eAG is calculated from the A1c and shown in mg/dL, the units of home glucose meters (NIDDK). The formula is eAG = 28.7 × A1c − 46.7 (Nathan 2008).
- No separate normal range. An A1c below 5.7% is normal (ADA Standards 2026, sec. 2), which is an eAG of about 114 mg/dL or less.
- It will not match a single meter reading, because it is a long-term average (NIDDK).
eAG to A1c chart
| eAG | A1c | ADA range |
|---|---|---|
| 97 mg/dL (5.4 mmol/L) | 5.0% | Normal range |
| 100 mg/dL (5.5 mmol/L) | 5.1% | Normal range |
| 103 mg/dL (5.7 mmol/L) | 5.2% | Normal range |
| 105 mg/dL (5.9 mmol/L) | 5.3% | Normal range |
| 108 mg/dL (6.0 mmol/L) | 5.4% | Normal range |
| 111 mg/dL (6.2 mmol/L) | 5.5% | Normal range |
| 114 mg/dL (6.3 mmol/L) | 5.6% | Normal range |
| 117 mg/dL (6.5 mmol/L) | 5.7% | Prediabetes range |
| 120 mg/dL (6.6 mmol/L) | 5.8% | Prediabetes range |
| 123 mg/dL (6.8 mmol/L) | 5.9% | Prediabetes range |
| 126 mg/dL (7.0 mmol/L) | 6.0% | Prediabetes range |
| 128 mg/dL (7.1 mmol/L) | 6.1% | Prediabetes range |
| 131 mg/dL (7.3 mmol/L) | 6.2% | Prediabetes range |
| 134 mg/dL (7.4 mmol/L) | 6.3% | Prediabetes range |
| 137 mg/dL (7.6 mmol/L) | 6.4% | Prediabetes range |
| 140 mg/dL (7.8 mmol/L) | 6.5% | Diabetes range |
eAG from the ADAG formula (Nathan 2008); ranges from the ADA diagnostic criteria (ADA Standards 2026, sec. 2). Other values: full A1c chart or the A1c calculator.
Where eAG comes from
The A1c-Derived Average Glucose (ADAG) study compared A1c with about 2,700 glucose readings per person over 3 months in 507 adults with type 1, type 2 or no diabetes (ADA Standards 2026, sec. 6). The link was strong (correlation 0.92), and the ADA and the American Association for Clinical Chemistry judged it strong enough to report eAG with the A1c (ADA Standards 2026, sec. 6). That straight-line relationship is the formula above (Nathan 2008).
How exact is it?
eAG is an average for many people. The ADA's table gives the range around each value (ADA Standards 2026, sec. 6):
| A1c | eAG | 95% range, mg/dL |
|---|---|---|
| 5% | 97 mg/dL | 76 to 120 |
| 6% | 126 mg/dL | 100 to 152 |
| 7% | 154 mg/dL | 123 to 185 |
| 8% | 183 mg/dL | 147 to 217 |
| 9% | 212 mg/dL | 170 to 249 |
| 10% | 240 mg/dL | 193 to 282 |
ADA Standards 2026, Table 6.1, adapted from the ADAG study (ADA Standards 2026, sec. 6).
The ADA also notes that these data come from a single study published in 2008, using an early CGM system, and that it is unclear how well they carry over to modern CGM (ADA Standards 2026, sec. 6). Anything that affects the A1c, such as changes in red blood cell turnover, affects the eAG in the same way (ADA Standards 2026, sec. 6); see when A1c can mislead.
eAG, meter readings and GMI
- Meter readings show glucose at one moment. eAG will not match them because it is a long-term average (NIDDK).
- Fasting glucose is a separate test after at least 8 hours without food (NIDDK), with its own cut points; see A1c vs fasting glucose.
- GMI goes the other way: it estimates an A1c-like number from CGM mean glucose. See the GMI vs A1c chart.
Frequently asked questions
What is a normal estimated average glucose?
There is no separate normal range for eAG: it is the A1c in other units. An A1c below 5.7% is normal, which works out to an eAG of about 114 mg/dL or less. The prediabetes range of 5.7% to 6.4% is about 117 to 137 mg/dL.
What does an estimated average glucose of 111 mean?
An eAG of 111 mg/dL comes from an A1c of 5.5%, which is in the normal range. 117 mg/dL comes from 5.7%, the start of the prediabetes range, and 126 mg/dL from 6.0%.
Why does my eAG not match my meter readings?
eAG is a long-term average over about 3 months, not the glucose level at one moment.
Is eAG the same as a fasting glucose?
No. eAG is calculated from the A1c and covers day and night, before and after meals. A fasting glucose is measured after at least 8 hours without food and has its own cut points.
Sources
- National Institute of Diabetes and Digestive and Kidney Diseases (NIH). The A1C Test & Diabetes. www.niddk.nih.gov/health-information/diagnostic-tests/a1c-test
- Nathan DM, Kuenen J, Borg R, Zheng H, Schoenfeld D, Heine RJ; A1c-Derived Average Glucose (ADAG) Study Group. Translating the A1C assay into estimated average glucose values. Diabetes Care. 2008;31(8):1473-1478. doi.org/10.2337/dc08-0545
- American Diabetes Association Professional Practice Committee. 6. Glycemic Goals, Hypoglycemia, and Hyperglycemic Crises: Standards of Care in Diabetes 2026. Diabetes Care. 2026;49(Suppl 1). doi.org/10.2337/dc26-S006
- American Diabetes Association Professional Practice Committee. 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes 2026. Diabetes Care. 2026;49(Suppl 1). doi.org/10.2337/dc26-S002
Written and maintained by the controla1clevels.com editorial team. We do not have a medical reviewer; every claim links to its primary source above. Last reviewed: 2026-10-28. Spotted an error? See About.