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Hemoglobin A1C (HbA1c) Test

What is a hemoglobin A1c (HbA1c) test?

A hemoglobin A1c (HbA1c) test measures the amount of blood sugar (glucose) attached to hemoglobin. Hemoglobin is the part of your red blood cells that carries oxygen from your lungs to the rest of your body. An HbA1c test shows what the average amount of glucose attached to hemoglobin has been over the past three months. It's a three-month average because that's typically how long a red blood cell lives.

If your HbA1c levels are high, it may be a sign of diabetes, a chronic condition that can cause serious health problems, including heart disease, kidney disease, and nerve damage.

Other names: HbA1c, A1c, glycohemoglobin, glycated hemoglobin, glycosylated hemoglobin

What is it used for?

An HbA1c test may be used to check for diabetes or prediabetes in adults. Prediabetes means your blood sugar levels show you are at risk for getting diabetes.

If you already have diabetes, an HbA1c test can help monitor your condition and glucose levels.

Why do I need an HbA1c test?

You may need an HbA1c test if you have symptoms of diabetes. These include:

  • Increased thirst
  • Increased urination
  • Blurred vision
  • Fatigue

Your health care provider may also order an HbA1c test if you are at higher risk for getting diabetes. Risk factors include:

What happens during an HbA1c test?

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

Will I need to do anything to prepare for the test?

You don't need any special preparations for an HbA1c test.

Are there any risks to the test?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

What do the results mean?

HbA1c results are given in percentages. Typical results are below.

  • Normal: HbA1c below 5.7%
  • Prediabetes: HbA1c between 5.7% and 6.4
  • Diabetes: HbA1c of 6.5% or higher

Your results may mean something different. If you have questions about your results, talk to your health care provider.

If you have diabetes, the American Diabetes Association recommends keeping your HbA1c levels below 7%. Your health care provider may have other recommendations for you, depending on your overall health, age, weight, and other factors.

Is there anything else I need to know about an HbA1c test?

The HbA1c test is not used for gestational diabetes, a type of diabetes that only affects pregnant women, or for diagnosing diabetes in children.

Also, if you have anemia or another type of blood disorder, an HbA1c test may be less accurate for diagnosing diabetes. If you have one of these disorders and are at risk for diabetes, your health care provider may recommend different tests.

References

  1. American Diabetes Association [Internet]. Arlington (VA): American Diabetes Association; c1995–2018. A1C and eAG [updated 2014 Sep 29; cited 2018 Jan 4]; [about 4 screens]. Available from: http://www.diabetes.org/living-with-diabetes/treatment-and-care/blood-glucose-control/a1c
  2. American Diabetes Association [Internet]. Arlington (VA): American Diabetes Association; c1995–2018. Common Terms [updated 2014 Apr 7; cited 2018 Jan 4]; [about 2 screens]. Available from: http://www.diabetes.org/diabetes-basics/common-terms
  3. Lab Tests Online [Internet]. American Association for Clinical Chemistry; c2001–2018. Diabetes [updated 2017 Dec 12; cited 2018 Jan 4]; [about 2 screens]. Available from: https://labtestsonline.org/conditions/diabetes
  4. Lab Tests Online [Internet]. American Association for Clinical Chemistry; c2001–2018. Hemoglobin A1c [updated 2018 Jan 4; cited 2018 Jan 4]; [about 2 screens]. Available from: https://labtestsonline.org/tests/hemoglobin-a1c
  5. Mayo Clinic [Internet]. Mayo Foundation for Medical Education and Research; c1998–2017. A1c test: Overview; 2016 Jan 7 [cited 2018 Jan 4]; [about 3 screens]. Available from: https://www.mayoclinic.org/tests-procedures/a1c-test/about/pac-20384643
  6. Merck Manual Consumer Version [Internet]. Kenilworth (NJ): Merck & Co. Inc.; c2018. Diabetes Mellitus (DM) [cited 2018 Jan 4]; [about 2 screens]. Available from: http://www.merckmanuals.com/home/hormonal-and-metabolic-disorders/diabetes-mellitus-dm-and-disorders-of-blood-sugar-metabolism/diabetes-mellitus-dm#v773034
  7. National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Blood Tests [cited 2018 Jan 4]; [about 3 screens]. Available from: https://www.nhlbi.nih.gov/health/health-topics/topics/bdt/with
  8. National Institute of Diabetes and Digestive and Kidney Diseases [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Diabetes Tests & Diagnosis; 2016 Nov [cited 2018 Jan 4]; [about 4 screens]. Available from: https://www.niddk.nih.gov/health-information/diabetes/overview/tests-diagnosis
  9. National Institute of Diabetes and Digestive and Kidney Diseases [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; The A1c Test & Diabetes; 2014 Sep [cited 2018 Jan 4]; [about 5 screens]. Available from: https://www.niddk.nih.gov/health-information/diabetes/overview/tests-diagnosis/a1c-test
  10. National Institute of Diabetes and Digestive and Kidney Diseases [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; What is Diabetes?; 2016 Nov [cited 2018 Jan 4]; [about 4 screens]. Available from: https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes
  11. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2018. Health Encyclopedia: A1c [cited 2018 Jan 4]; [about 2 screens]. Available from: https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=A1C
  12. UW Health [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; c2018. Glycohemoglobin (HbA1c, A1c): Results [updated 2017 Mar 13; cited 2018 Jan 4]; [about 8 screens]. Available from: https://www.uwhealth.org/health/topic/medicaltest/hemoglobin-a1c/hw8432.html#hw8441
  13. UW Health [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; c2018. Glycohemoglobin (HbA1c, A1c): Test Overview [updated 2017 Mar 13; cited 2018 Jan 4]; [about 2 screens]. Available from: https://www.uwhealth.org/health/topic/medicaltest/hemoglobin-a1c/hw8432.html

The medical information provided is for informational purposes only, and is not to be used as a substitute for professional medical advice, diagnosis or treatment. Please contact your health care provider with questions you may have regarding medical conditions or the interpretation of test results.

In the event of a medical emergency, call 911 immediately.