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Diabetes marker · HbA1c

What does hemoglobin A1c mean on your blood test?

The A1c test shows your average blood sugar over the past two to three months in a single percentage. It is used to screen for and manage diabetes. Here is how to read your number.

Normal
Below 5.7
%
Prediabetes
5.7–6.4
%
Diabetes
6.5 and above
%

What A1c measures

Hemoglobin A1c, sometimes written HbA1c, reflects the amount of sugar attached to the hemoglobin in your red blood cells. Because red blood cells live for around three months, the A1c gives an average of your blood sugar over that window rather than a single moment. It is reported as a percentage.

How to read your A1c

An A1c below 5.7% is in the normal range. A result of 5.7% to 6.4% falls in the prediabetes range, and 6.5% or higher on two separate tests is used to diagnose diabetes. If you already have diabetes, your clinician uses A1c to see how well your management plan is working over time, often with a personal target.

What your result can mean

A higher A1c means your average blood sugar has been higher. Some conditions that affect red blood cells can make A1c less reliable, which is one reason your clinician may confirm with other tests. A single number is a starting point for a conversation, not a verdict.

See your own A1c explained

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Common questions

Do I need to fast for an A1c test?
No. Unlike a fasting glucose test, A1c does not require fasting because it reflects an average over months rather than your level at that moment. You can usually have it done at any time of day.
What A1c means prediabetes?
An A1c between 5.7% and 6.4% is in the prediabetes range. A result of 6.5% or higher, confirmed on a second test, is used to diagnose diabetes. Your clinician confirms and interprets the result for you.
How often should A1c be checked?
That depends on your situation. People managing diabetes are often tested a few times a year, while screening frequency for others depends on risk factors. Your clinician will advise what is right for you.

Related guides

Blood glucose, explained
What a fasting glucose result means
Triglycerides, explained
A blood fat linked to metabolic health
LDL cholesterol, explained
The “bad” cholesterol and what high means

Sources

  1. MedlinePlus [Internet]. Bethesda (MD): National Library of Medicine (US); Hemoglobin A1c (HbA1c) Test; [cited 2026 Jul 9]. Available from: https://medlineplus.gov/lab-tests/hemoglobin-a1c-hba1c-test/
  2. MedlinePlus [Internet]. Bethesda (MD): National Library of Medicine (US); A1C; [cited 2026 Jul 9]. Available from: https://medlineplus.gov/a1c.html
  3. National Institute of Diabetes and Digestive and Kidney Diseases (US); The A1C Test & Diabetes; [cited 2026 Jul 9]. Available from: https://www.niddk.nih.gov/health-information/diagnostic-tests/a1c-test

Content last reviewed 9 July 2026. Reference ranges vary by laboratory; always read your results against the range printed on your own report.

This page explains a common lab marker in general terms using public information from the U.S. National Library of Medicine and other NIH sources. It is educational and is not a diagnosis or medical advice. Reference ranges differ between laboratories and the meaning of a result depends on your age, sex, medications, and overall health. Always discuss your own results with the clinician who ordered them.