HbA1c is a lab test that shows the average amount of sugar in your blood over 3 months. It shows how well you are controlling your diabetes.
Glycated hemoglobin; Glycosylated hemoglobin; Hemoglobin - glycosylated; A1C; GHb; Glycohemoglobin; Diabetic control index
How the Test is Performed
A blood sample is needed. For information on how this is done, see: Venipuncture.
How to Prepare for the Test
No special preparation is needed.
How the Test Will Feel
When the needle is inserted, you may feel a slight pinch or some stinging. Afterward, there may be some throbbing.
Why the Test is Performed
Your doctor may order this test if you have diabetes. It shows how well you are controlling your diabetes.
The test may also be used to screen for diabetes.
An HbA1c of 6% or less is normal.
The following are the results when the HbA1c is being used to diagnose diabetes:
- Normal: Less than 5.7%
- Pre-diabetes: 5.7% to 6.4%
- Diabetes: 6.5% or higher
If you have diabetes, try to keep your level at or below 7%. You and your health care provider must decide what a normal level is for you.
Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.
What Abnormal Results Mean
Abnormal results mean that you have had high blood sugar levels over a period of weeks to months.
If your HbA1c is above 6.5% and you do not already have diabetes, you may be diagnosed with diabetes.
If your level is above 7% and you have diabetes, it means that your diabetes control may not be as good as it should be.
In general, the higher your HbA1c, the higher the risk that you will develop problems such as:
If your HbA1c stays high for a long period of time, the risk for these problems is even greater.
Ask your doctor how often you should have your level tested. Usually, doctors recommend testing every 3 or 6 months.
Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight, but may include:
- Excessive bleeding
- Fainting or feeling light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
American Diabetes Association. Standards of medical care in diabetes--2011. Diabetes Care. 2011 Jan;34 Suppl 1:S11-61.
Ari S. Eckman, MD, Chief, Division of Endocrinology, Diabetes and Metabolism, Trinitas Regional Medical Center, Elizabeth, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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