HbA1c
Hemoglobin A1c
HbA1c measures how much sugar is attached to hemoglobin, the protein inside red blood cells. It reflects your average blood sugar over about two to three months, rather than just the day of the test.
What does a high HbA1c mean?
A higher HbA1c usually means blood sugar has been higher over the past few months. It can help identify diabetes or check how treatment is working. Some blood conditions make the result less reliable.
Diagnostic thresholds are different from treatment goals
- Below the prediabetes threshold
- Below 5.7% (39 mmol/mol)
- Prediabetes range
- 5.7–6.4% (39–47 mmol/mol)
- Diabetes range
- 6.5% or more (48 mmol/mol or more)
These thresholds are used to assess non-pregnant adults for diabetes. A result in the diabetes range usually needs confirmation. If you already have diabetes, your clinician sets a separate treatment goal based on your circumstances.
Sources: NIDDK (NIH)
What can change this result?
What can raise it
- Regularly having sugary drinks or carb portions that push your blood sugar up.
- Being less active, which can make it harder for your body to use blood sugar.
- Diabetes that is untreated or needs a change in treatment.
What can help lower it
- Choosing unsweetened drinks and balancing carb portions with vegetables, protein and fiber.
- Building regular movement into your week, such as walking.
- Taking diabetes medicines as prescribed, if you need them.
HbA1c reflects months of blood sugar, so one meal does not explain it. Anemia, pregnancy, some kidney conditions or a recent transfusion can change the reading without the same change in glucose.
What should I do next?
- Ask whether the result needs a repeat test or confirmation with a glucose test.
- Mention anemia, transfusions or known hemoglobin conditions, especially if HbA1c does not match your glucose readings.
- If you have diabetes, agree on your personal goal and when to repeat the test.
How this test works
Sugar attaches to hemoglobin during the life of a red blood cell. Recent weeks influence the result more than earlier weeks. Conditions that alter red blood cells can change HbA1c independently of blood sugar.