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Glycosylated Hemoglobin Test
(HbA1c; GHb; Glycohemoglobin; Diabetic Control Index)
A glycosylated hemoglobin test (HbA1c) is a blood test that measures the amount of glycosylated hemoglobin in the blood. Hemoglobin is a protein found in the blood. Glycosylated hemoglobin means that glucose (sugar) has attached to the hemoglobin protein. The higher your blood sugar is, the more that glucose gets attached to your hemoglobin.
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Reasons for Test
HbA1c shows how high your blood sugar levels have been during the past three months. This can help your doctor determine how well you are controlling your diabetes. Your doctor may also use HbA1c to test you for diabetes.
What to Expect
Description of Test
You will be asked to sit. An area inside your elbow will be cleaned with an antiseptic wipe. A large band will be tied around your arm. The needle will then be inserted into a vein. A tube will collect the blood from the needle. The band on your arm will be removed. After all the blood is collected, the needle will be removed. Some gauze will be placed over the site to help stop bleeding. You may also be given a bandage to place over the site. The process takes about 5-10 minutes.
Apply pressure to the site until bleeding stops.
How Long Will It Take?
Less than five minutes
Will It Hurt?
It may hurt slightly when the needle is inserted.
Talk to your doctor about what goal is right for you. If your HbA1c levels are high, you may need a change in treatment, such as:
- Changing your medications
- Increasing your level of physical activity
- Modifying your diet
Talk with your doctor about when you should be tested again.
Call Your Doctor
After the test, call your doctor if any of the following occurs:
- Persistent bleeding or discharge
In case of an emergency, call for emergency medical services right away.
American Diabetes Association
National Diabetes Education Program
Canadian Diabetes Association
American Diabetes Association. Standards of medical care in diabetes—2008. Diabetes Care. 2008;31:S12-S54.
Aronow WS, Ahn C, Weiss MB, Babu S. Relation of increased hemoglobin A1c levels to severity of peripheral arterial disease in patients with diabetes mellitus. Am J Cardiol. 2007;99:1468-1469.
Check your hemoglobin A1c IQ. National Diabetes Education Program website. Available at: http://nfb.org/Images/nfb/Publications/vodold/vspr9905.htm. Accessed September 29, 2014.
A new number. American Diabetes Association website. Available at: http://forecast.diabetes.org/magazine/features/new-number. Published November 2008. Accessed September 29, 2014.
Pradhan AD, Rifai N, Buring JE, Ridker PM. Hemoglobin A1c predicts diabetes but not cardiovascular disease in nondiabetic women. Am J Med. 2007;120:720-727.
Saudek CD, Herman WH, Sacks DB, et al. A new look at screening and diagnosing diabetes mellitus. J Clin Endocrinol Metab. 2008;93:2447-2453.
American Diabetes Association. Standards of medical care in diabetes mellitus. Diabetes Care. 21003 Jan;26 Suppl 1:s33-50. Available at: http://care.diabetesjournals.org/content/26/suppl%5F1/s33.full. Accessed September 29, 2014.
- Reviewer: Kim Carmichael, MD
- Review Date: 08/2014
- Update Date: 09/29/2014