Glycosylated Hemoglobin Test

(HbA1c; GHb; Glycohemoglobin; Diabetic Control Index)

by Urmila R. Parlikar, MS

Definition

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.

Glycohemoglobin

glucose and RBC
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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.

Possible Complications    TOP

There are no major complications associated with this test.

What to Expect    TOP

Description of Test

You will roll up your sleeve. An elastic band will be wrapped around your upper arm. An area on your arm will be cleaned with alcohol. The needle will then be inserted into your arm. A small amount of blood will be drawn into a tube. The needle will be removed. Pressure will be applied to the puncture site. A small bandage may be placed on the site. Your blood will be sent to a lab for testing.

After Test

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.

Results

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 medicines
  • Increasing your level of physical activity
  • Modifying your diet

Talk with your doctor about when you should be tested again.

Call Your Doctor    TOP

After the test, call your doctor if any of the following occurs:

  • Bleeding from the puncture site
  • Red, swollen, or painful puncture site
  • If you have not heard from your doctor in 1-2 weeks
In case of an emergency, call for medical help right away.

RESOURCES:

American Diabetes Association
http://www.diabetes.org
National Diabetes Education Program
http://ndep.nih.gov

CANADIAN RESOURCES:

Canadian Diabetes Association
http://www.diabetes.ca/
Health Canada
http://www.hc-sc.gc.ca/index-eng.php

References:

A1C Test. Mayo Clinic website. Available at: http://www.mayoclinic.com/health/a1c-test/MY00142 . Updated January 21, 2011. Accessed July 31, 2012.
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 July 31, 2012.
A new number. American Diabetes Association website. Available at: http://forecast.diabetes.org/magazine/features/new-number . Accessed July 31, 2012.
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.
Standards of medical care in diabetes mellitus. American Diabetes Association website. Available at: http://care.diabetesjournals.org/content/26/suppl_1/s33.full . Accessed July 31, 2012.
Last reviewed September 2013 by Kim Carmichael, MD
Last Updated: 9/30/2013