Top of the page
A glycohemoglobin test, or hemoglobin A1c, is a blood test that checks the amount of sugar (glucose) bound to the hemoglobin in the red blood cells. People who have diabetes or other conditions that increase their blood glucose levels have more glycohemoglobin (sugar bound to hemoglobin) than normal.
An A1c test can be used to diagnose prediabetes or diabetes. The A1c test checks the long-term control of blood glucose levels in people with diabetes. Most doctors think checking an A1c level is the best way to check how well a treatment plan is working. This test can be done with a blood draw from a vein. Sometimes an A1c test can be done with blood from a finger stick.
A home blood glucose test measures the level of blood glucose only at that moment. Blood glucose levels change during the day for many reasons, including medicine, diet, exercise, and the level of insulin in the blood.
It is useful for a person who has diabetes to have information about the long-term control of blood sugar levels. The A1c test result does not change with any recent changes in diet, exercise, or medicines.
Glucose binds to hemoglobin in red blood cells at a steady rate. Since red blood cells last 3 to 4 months, the A1c test shows how much glucose is in the plasma part of blood. This test shows how well your diabetes has been managed in the last 2 to 3 months and whether your diabetes treatment plan needs to be changed. This test may not be accurate for everyone because many things can affect the lifespan of red blood cells, such as the second or third trimester of pregnancy, a recent blood loss or a blood transfusion, sickle cell disease, hemodialysis, or erythropoietin (ESA) medicine.
The A1c test can also help your doctor see how big your risk is of developing problems from diabetes, such as kidney failure, vision problems, and leg or foot numbness. Keeping your A1c level in your target range can lower your chance for problems.
The A1c test is one of the tests used to diagnose prediabetes and diabetes. If you have diabetes, this test is done to check how well your diabetes has been managed over the past 2 to 3 months. Your doctor can use this information to adjust your treatment, if needed.
You don't need to stop eating before you have an A1c test. This test can be done at any time during the day, even after a meal.
A health professional uses a needle to take a blood sample, usually from an arm. It can also be done using blood from a finger stick.
You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
There is very little chance of having a problem from this test. A small bruise may form at the site.
Diabetes Canada recommends that most non-pregnant adults who have diabetes and children who have type 2 diabetes have an A1c level of 7.0%. There is evidence to suggest that for children with type 2 diabetes, having an A1c of <6.0% within the first 6 months of diagnosis may reduce the risk of treatment failure. Diabetes Canada recommends that most children who have type 1 diabetes have an A1c level of 7.5% or less. Talk to your doctor about your diabetes treatment plan and your target A1c goal.
Adaptation Date: 11/1/2022
Adapted By: Alberta Health Services
Adaptation Reviewed By: Alberta Health Services
To learn more about Healthwise, visit Healthwise.org.
© 1995-2023 Healthwise, Incorporated. All rights reserved. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.