Typical reference ranges
| Category | HbA1c (%) | mmol/mol | Average glucose (eAG) |
|---|---|---|---|
| Normal | Below 5.7 | Below 39 | Below about 117 mg/dL (6.5 mmol/L) |
| Prediabetes (ADA) | 5.7–6.4 | 39–47 | 117–137 mg/dL (6.5–7.6 mmol/L) |
| Prediabetes (NICE, UK) | 6.0–6.4 | 42–47 | 126–137 mg/dL |
| Diabetes | 6.5 or higher | 48 or higher | 140 mg/dL (7.8 mmol/L) or higher |
| Common target in diabetes (ADA) | 7.0 or less | 53 or less | 154 mg/dL (8.6 mmol/L) or less |
Ranges based on: MedlinePlus; American Diabetes Association; NICE PH38. Full references are listed at the end of this page.
Use your own lab's range. Reference ranges differ between labs, analysers and methods, and with age, sex and pregnancy. The range printed on your report takes priority over the figures here.
Check your value
Type the HbA1c result from your report to see where it sits against the typical ranges on this page. Nothing is sent or saved.
General information only, not a diagnosis. Your lab's printed range takes priority.
HbA1c Calculator
HbA1c % ↔ mmol/mol and estimated average glucose (eAG).
Blood Sugar Converter
Convert glucose between mg/dL and mmol/L with normal ranges.
How HbA1c works
Glucose sticks to hemoglobin inside red cells. Red cells live about 120 days, so the share of glycated hemoglobin reflects the average sugar level over roughly the past 8–12 weeks, weighted towards the most recent month.
Diagnosing diabetes
The WHO, ADA and NICE all accept an HbA1c of 6.5% (48 mmol/mol) or more as diagnostic of diabetes. Without clear symptoms, the result should be confirmed with a second test. Following the WHO's 2011 advice, HbA1c is not used for diagnosis in children and young people, in anyone suspected of type 1 diabetes, when symptoms have lasted less than two months, during acute illness or after pancreatic damage, in pregnancy, or when a condition affects the HbA1c measurement.
When HbA1c can mislead
- Falsely low: recent blood loss or transfusion, hemolysis, pregnancy, chronic kidney disease, some anaemias.
- Falsely high: iron deficiency anaemia and B12 deficiency (older red cells).
- Hemoglobin variants such as HbS, HbC and HbE, and thalassaemia, can interfere with some methods. Ask your lab which method it uses if you carry a variant.
In these situations fasting glucose or an oral glucose tolerance test is used instead.
Converting % to mmol/mol
mmol/mol = (% − 2.15) × 10.929. For example, 7% is 53 mmol/mol and 8% is 64 mmol/mol. The HbA1c calculator on this site does this for you and gives the estimated average glucose.
Frequently asked questions
Do I need to fast for HbA1c?
No. It can be taken at any time of day.
What is a good HbA1c for a diabetic?
The ADA recommends 7% (53 mmol/mol) or less for most adults, but targets are set individually; older or frail people may have higher targets.
How often should HbA1c be checked?
Every 3 months when treatment is changing, and every 6 months when stable.
Is 6.0 HbA1c diabetes?
No. It is in the prediabetes range by ADA and NICE criteria.
Sources and references
- MedlinePlus: Hemoglobin A1C (HbA1c) Test
- American Diabetes Association: Understanding A1C
- NICE PH38: Type 2 diabetes, prevention in people at high risk
- ADA: Diabetes diagnosis and tests
- Diabetes UK: WHO criteria for using HbA1c to diagnose diabetes