HbA1c and estimated average glucose
HbA1c reflects your blood sugar over the past 2 to 3 months. Turn it into an average glucose, or the other way round, and switch between % and mmol/mol.
Convert a value
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Conversion result
HbA1c
Your entry
7.0%
53mmol/mol
(7 − 2.15) × 10.929 = 53
Estimated average glucose
8.6mmol/L
(28.7 × 7 − 46.7) ÷ 18.016 = 8.6
154mg/dL
28.7 × 7 − 46.7 = 154
HbA1c: 7.0 %, 53 mmol/mol. Estimated average glucose: 8.6 mmol/L, 154 mg/dL
Where these calculations come from
- HbA1c and average glucose: formula from the ADAG study (Nathan et al., Diabetes Care, 2008)
- HbA1c in % and in mmol/mol: IFCC equation (Hoelzel et al., Clinical Chemistry, 2004)
- mmol/L and mg/dL: 1 mmol/L = 18.016 mg/dL, from the molar mass of glucose (180.16 g/mol) (PubChem, National Library of Medicine)
- g/L and mg/dL: 1 g/L = 100 mg/dL, a plain change of unit
Applidia does not invent any formula: we apply these published references as they are.
The maths runs in your browser. This does not replace the advice of your doctor or diabetes care team.
HbA1c and average glucose chart
| HbA1c (%) | HbA1c (mmol/mol) | Average (mmol/L) | Average (mg/dL) |
|---|---|---|---|
| 5.0 | 31 | 5.4 | 97 |
| 5.5 | 37 | 6.2 | 111 |
| 5.7 | 39 | 6.5 | 117 |
| 6.0 | 42 | 7.0 | 126 |
| 6.5 | 48 | 7.8 | 140 |
| 7.0 | 53 | 8.6 | 154 |
| 7.5 | 58 | 9.4 | 169 |
| 8.0 | 64 | 10.2 | 183 |
| 8.5 | 69 | 10.9 | 197 |
| 9.0 | 75 | 11.7 | 212 |
| 9.5 | 80 | 12.5 | 226 |
| 10.0 | 86 | 13.3 | 240 |
| 11.0 | 97 | 14.9 | 269 |
| 12.0 | 108 | 16.5 | 298 |
| 13.0 | 119 | 18.1 | 326 |
Values calculated with the ADAG formula (Nathan et al., 2008) and the IFCC equation (Hoelzel et al., 2004).
% or mmol/mol?
% is still the most common unit in Switzerland, France and the United States. mmol/mol, the international reference unit, is the standard in the UK and appears more and more often next to %.
Reference values
| Landmark | HbA1c (%) | mmol/mol |
|---|---|---|
| Usual value without diabetesADA | < 5.7 | < 39 |
| Prediabetes rangeADA | 5.7–6.4 | 39–47 |
| Diagnostic threshold for diabetesWHO 2011, ADA | ≥ 6.5 | ≥ 48 |
| Common general target for adults with diabetes, tailored to each personADA | < 7.0 | < 53 |
These are published thresholds, given as landmarks: agree on your personal target with your care team. Different landmarks apply during pregnancy and in children.
When HbA1c can mislead
HbA1c also depends on how long red blood cells live. It can be skewed in particular by:
- anaemia, iron deficiency or recent blood loss
- a haemoglobin variant (for example sickle cell trait)
- pregnancy
- advanced kidney disease or a recent transfusion
Sources (7)
- Nathan D. M. et al. (ADAG Study Group). Translating the A1C Assay Into Estimated Average Glucose Values. Diabetes Care 2008;31:1473–1478. doi.org/10.2337/dc08-0545
- Hoelzel W. et al. IFCC Reference System for Measurement of Hemoglobin A1c in Human Blood and the National Standardization Schemes in the United States, Japan, and Sweden. Clin Chem 2004;50:166–174. doi.org/10.1373/clinchem.2003.024802
- National Library of Medicine. PubChem Compound Summary: Glucose (CID 5793). Molecular weight 180.16 g/mol. pubchem.ncbi.nlm.nih.gov/compound/Glucose
- American Diabetes Association Professional Practice Committee. 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes 2026. Diabetes Care 2026;49(Suppl. 1):S27–S49. doi.org/10.2337/dc26-S002
- 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):S132–S149. doi.org/10.2337/dc26-S006
- World Health Organization. Use of glycated haemoglobin (HbA1c) in the diagnosis of diabetes mellitus. Geneva, 2011.
- Bergenstal R. M. et al. Glucose Management Indicator (GMI): A New Term for Estimating A1C From Continuous Glucose Monitoring. Diabetes Care 2018;41:2275–2280. doi.org/10.2337/dc18-1581
Frequently asked questions
How is HbA1c converted into average glucose?
With the formula from the international ADAG study (2008): average glucose (mg/dL) = 28.7 × HbA1c (%) − 46.7. The study compared the HbA1c of more than 500 people with their glucose readings over 3 months. For mmol/mol, the IFCC equation is: (HbA1c (%) − 2.15) × 10.929.
Why does my sensor show a different number (GMI)?
GMI (glucose management indicator) is worked out from the sensor’s average with a different formula (Bergenstal et al., 2018). It can differ from your lab HbA1c. Both are useful and worth discussing with your care team.
Is the estimated average glucose exact?
It is an estimate. For the same HbA1c, the real average glucose varies from one person to another. It helps you link your HbA1c to the numbers you see on your meter.
