What it measures
Sugar in the blood attaches to haemoglobin, the protein inside red blood cells. Red cells live for about three months, so the share of haemoglobin carrying sugar — HbA1c — reflects the average blood-sugar level over roughly the past three months.
Why it is used
- To screen for or help diagnose diabetes and prediabetes, alongside other tests.
- To follow how well diabetes is controlled over time.
Unlike a fasting glucose test, it usually needs no fasting.
What can affect it
Conditions that change red blood cells — for example some types of anaemia or inherited haemoglobin variants — can make the result less accurate. Your clinician may choose a different test in those cases.
Talking about the result
Targets and thresholds depend on the person, their age and their health. Discuss your result, and any plan based on it, with the clinician who ordered the test.
Sources
- Hemoglobin A1C (HbA1c) Test — MedlinePlus — U.S. National Library of Medicine. Checked 2026-09-26.
Editorial update: 2026-09-26.
Medical disclaimer: this is a source-linked educational summary, not individual medical advice, diagnosis, prescription or interpretation of personal results. For severe or rapidly worsening symptoms, call 115.
Antopeloni — plain-language health education from public sources, part of the ZIBADIS network founded by Masoud Moghaddam.
