Hemoglobin A1c Test

About this test

This test measures your average blood sugar level over the past 2 to 3 months by looking at what percentage of your hemoglobin has become coated with sugar (glycated). It's the standard test used to screen for prediabetes and diabetes, and to monitor how well blood sugar is being managed over time.

Unlike a fasting glucose test, which captures a single moment, the A1c gives a longer-term view. An A1c below 5.7% is considered normal; 5.7–6.4% is the prediabetes range; 6.5% or above on two separate tests typically indicates diabetes. Certain conditions affecting red blood cells (such as sickle cell trait or anemia) can sometimes affect accuracy, and your clinician can advise whether additional testing is needed.

Components

• Hemoglobin A1c (HbA1c): The percentage of hemoglobin proteins in your red blood cells that have glucose (sugar) attached to them. Because red blood cells live about 90 days, this percentage reflects your average blood sugar over that period — not just what you ate recently.

Who is this test for?

Recommended for adults 35–45 and older as part of routine diabetes screening, and for anyone who is overweight, has a family history of type 2 diabetes, or has been told they have prediabetes. It is also the standard monitoring test for people already managing diabetes. Major medical guidelines suggest screening every three years for average-risk adults and more frequently if risk factors are present.