Hemoglobin A1C (HbA1c) Test
Reviewed
Also called: A1C, HbA1c, Glycated haemoglobin, Glycohemoglobin
A hemoglobin A1C (HbA1C) test is a blood test that shows your average level of blood glucose, also called blood sugar, over the past two to three months.
Specimen: Blood
Why this test may be ordered
- Screening or diagnosis of type 2 diabetes or prediabetes
- Monitoring diabetes over time
- Assessing longer-term glucose trends alongside other information
Preparation and collection
Certain medicines such as opioids and some HIV medicines may affect your results, so tell your provider about everything you take. But don't stop taking any medicines unless your provider tells you to.
A health care professional will take a blood sample from a vein in your arm, using a small needle. This usually takes less than five minutes.
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
Understanding results
A1C results tell you what percentage of your hemoglobin is coated with glucose. The ranges are just a guide to what is normal.
- Normal: A1C below 5.7%: The ranges are just a guide to what is normal. What's normal for you depends on your health, age, and other factors. Limitation: Also, if you have a condition that affects your red blood cells, such as anemia or another type of blood disorder, an A1C test may not be accurate for diagnosing diabetes. Next step: Ask your provider what A1C percentage is healthy for you.
What does a high A1C mean?
Prediabetes: A1C between 5.7% and 6.4%, or diabetes: A1C of 6.5% or higher: High A1C levels are a sign of high blood glucose from diabetes. Limitation: Providers often use more than one test to diagnose diabetes. Next step: So, if your test result was higher than normal, you may have another A1C test or a different type of diabetes test, usually either a fasting blood glucose test or an oral glucose tolerance test (OGTT).
- HbA1c does not show short-term glucose swings or a current glucose level.
- It is not used by itself for every diabetes type or during every pregnancy situation.
What to do next
Ask your provider what A1C percentage is healthy for you. If your A1C test was done to monitor your diabetes, talk with your provider about what your test results mean.
- Which reference interval and units apply to my result?
- Could medicines, supplements, illness, or sample timing affect this result?
- Do I need a repeat test or another test before any conclusion is made?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.
U.S. National Library of Medicine: Hemoglobin A1C (HbA1c) Test