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By Mayo Clinic staffFor someone who doesn't have diabetes, a normal A1C level can range from 4.5 to 6 percent. Someone who's had uncontrolled diabetes for a long time might have an A1C level above 9 percent.
When the A1C test is used to diagnose diabetes, an A1C level of 6.5 percent or higher on two separate tests indicates you have diabetes. A result between 5.7 and 6.4 percent is considered prediabetes, which indicates a high risk of developing diabetes.
For most people who have previously diagnosed diabetes, an A1C level of 7 percent or less is a common treatment target. Higher targets may be chosen in some individuals. If your A1C level is above your target, your doctor may recommend a change in your diabetes treatment plan. Remember, the higher your A1C level, the higher your risk of diabetes complications.
Here's how A1C level corresponds to average blood sugar level, in milligrams per deciliter (mg/dL) and millimoles per liter (mmol/L):
| A1C level | Average blood sugar level |
|---|---|
| 5 percent | 80 mg/dL (4.4 mmol/L) |
| 6 percent | 120 mg/dL (6.7 mmol/L) |
| 7 percent | 150 mg/dL (8.3 mmol/L) |
| 8 percent | 180 mg/dL (10 mmol/L) |
| 9 percent | 210 mg/dL (11.7 mmol/L) |
| 10 percent | 240 mg/dL (13.3 mmol/L) |
| 11 percent | 270 mg/dL (15 mmol/L) |
| 12 percent | 300 mg/dL (16.7 mmol/L) |
| 13 percent | 333 mg/dL (18.5 mmol/L) |
| 14 percent | 360 mg/dL (20 mmol/L) |
It's important to note that the effectiveness of A1C tests may be limited in certain cases. For example:
- If you experience heavy or chronic bleeding, your hemoglobin stores may be depleted. This may make your A1C test results falsely low.
- If you don't have enough iron in your bloodstream, your A1C test results may be falsely high.
- Most people have only one type of hemoglobin, called hemoglobin A. If you have an uncommon form of hemoglobin (known as a hemoglobin variant), your A1C test result may be falsely high or falsely low. Hemoglobin variants are most often found in blacks and people of Mediterranean or Southeast Asian heritage. Hemoglobin variants can be confirmed with lab tests. If you're diagnosed with a hemoglobin variant, your A1C tests may need to be done at a specialized lab for the most accurate results.
Also keep in mind that the normal range for A1C results may vary somewhat among labs. If you consult a new doctor or use a different lab, it's important to consider this possible variation when interpreting your A1C test results.
- A1c and eAG. American Association for Clinical Chemistry. http://www.labtestsonline.org/understanding/analytes/a1c/test.html. Accessed May 6, 2010
- A1C test. American Diabetes Association. http://www.diabetes.org/living-with-diabetes/treatment-and-care/blood-glucose-control/a1c/. Accessed May 6, 2010.
- McCulloch D. Screening for diabetes mellitus. http://www.uptodate.com/home/index.html. Accessed May 6, 2010.
- McCulloch D. Estimation of blood glucose control in diabetes mellitus. http://www.uptodate.com/home/index.html. Accessed May 6, 2010.
- For people of African, Mediterranean, or Southeast Asian heritage: Important information about diabetes blood tests. National Institute of Diabetes and Digestive and Kidney Diseases. http://diabetes.niddk.nih.gov/dm/pubs/traitA1C/index.htm. Accessed May 6, 2010.
- Nathan DM, et al. International Expert Committee report on the role of the A1C assay in the diagnosis of diabetes. Diabetes Care. 2009;32:1327.
- Standards of medical care in diabetes — 2011. Diabetes Care. 2011;34(suppl):1.
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