Hemoglobin A1C (HbA1c) Test
Reviewed
HbA1c estimates average blood glucose exposure over roughly the previous two to three months.
Preparation and collection
Fasting is usually not required for HbA1c alone. Follow instructions for any additional tests.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- 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
Depending on the purpose and result, follow-up may include repeat HbA1c, fasting glucose, an oral glucose tolerance test, or treatment review.
Evidence source
U.S. National Library of Medicine: Hemoglobin A1C (HbA1c) Test