HbA1c to Average Blood Glucose Conversion Chart
The American Diabetes Association provides a standardized conversion table showing that each 1% increase in HbA1c corresponds to approximately a 29 mg/dL increase in average blood glucose, based on the international ADAG study of 2,700 glucose measurements in 507 adults. 1, 2
Standard Conversion Table
| HbA1c (%) | Average Blood Glucose (mg/dL) | Average Blood Glucose (mmol/L) |
|---|---|---|
| 5 | 97 (76–120) | 5.4 (4.2–6.7) |
| 6 | 126 (100–152) | 7.0 (5.5–8.5) |
| 7 | 154 (123–185) | 8.6 (6.8–10.3) |
| 8 | 183 (147–217) | 10.2 (8.1–12.1) |
| 9 | 212 (170–249) | 11.8 (9.4–13.9) |
| 10 | 240 (193–282) | 13.4 (10.7–15.7) |
| 11 | 269 (217–314) | 14.9 (12.0–17.5) |
| 12 | 298 (240–347) | 16.5 (13.3–19.3) |
Values in parentheses represent 95% confidence intervals 1, 2
Mathematical Formula
The conversion formula is: Average Glucose (mg/dL) = 28.7 × HbA1c (%) – 46.7, derived from the ADAG study which demonstrated a strong correlation (r = 0.92) between HbA1c and mean glucose concentrations. 2, 3
An online calculator for converting A1C results into estimated average glucose (eAG) in either mg/dL or mmol/L is available at professional.diabetes.org/eAG. 1
Evidence Base and Strength
The ADAG study analyzed approximately 2,700 glucose measurements collected over three months per HbA1c value in 507 adults with type 1 diabetes, type 2 diabetes, and individuals without diabetes, providing the empirical foundation for this conversion. 2, 3
Both the American Diabetes Association and the American Association for Clinical Chemistry recommend that laboratory reports present both the HbA1c value and the corresponding estimated average glucose to aid patient understanding. 2
Critical Limitations—When This Chart Is Unreliable
Do not use this conversion in patients with conditions affecting red blood cell turnover, as the HbA1c will not accurately reflect true glycemic control: 2, 3
- Hemolytic anemia or other anemias 2
- Glucose-6-phosphate dehydrogenase deficiency 2
- Recent blood transfusion 2
- Erythropoiesis-stimulating agents 2
- End-stage kidney disease 2, 3
- Pregnancy (second and third trimesters) 3
- Sickle-cell disease (HbSS) or homozygous hemoglobin variants—HbA1c cannot be measured because these individuals lack measurable HbA 2
What This Chart Does NOT Tell You
Estimated average glucose reflects only the average glucose concentration and provides no information about glycemic variability, hypoglycemia risk, or glucose excursions. 2, 3
Two patients with identical HbA1c values may have vastly different glucose patterns—one with stable glucose and another with dangerous swings between hypoglycemia and hyperglycemia. 3
Racial and Ethnic Considerations
African-American individuals may exhibit slightly higher HbA1c values than non-Hispanic White individuals for the same mean glucose level, though the ADAG study showed no statistically significant differences. 2, 3
Afro-Caribbean populations have shown lower HbA1c relative to glucose in some studies. 2
Alternative Monitoring When HbA1c Is Unreliable
In situations where HbA1c interpretation is compromised by the conditions listed above, use self-monitoring of blood glucose (SMBG), continuous glucose monitoring (CGM), or glycated serum protein assays such as fructosamine or glycated albumin. 1, 2
- Fructosamine and glycated albumin reflect glycemia over the past 2–4 weeks, a shorter time frame than HbA1c, and may be particularly useful for patients with significant glycemic variability or type 1 diabetes. 1, 2
Clinical Context for Target Goals
- The American Diabetes Association recommends an HbA1c goal of <7% (<53 mmol/mol) for many nonpregnant adults, which corresponds to an estimated average glucose below 154 mg/dL. 1