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By Mayo Clinic staffAn international committee of experts from the American Diabetes Association, the European Association for the Study of Diabetes and the International Diabetes Federation recommends that the A1C test be the primary test used to diagnose prediabetes, type 1 diabetes and type 2 diabetes.
After a diabetes diagnosis, the A1C test is used to monitor your diabetes treatment plan. Since the A1C test measures your average blood sugar level for the past two to three months instead of your blood sugar level at a point in time, it is a better reflection of how well your diabetes treatment plan is working overall.
Your doctor will likely use the A1C test when you're first diagnosed with diabetes. This also helps establish a baseline A1C level. The test may then need to be repeated while you're learning to control your blood sugar.
Later, how often you need the A1C test depends on the type of diabetes you have, your treatment plan and how well you're managing your blood sugar. For example, the A1C test may be recommended:
- Twice a year if you have type 2 diabetes, you don't use insulin, and your blood sugar level is consistently within your target range
- Three to four times a year if you have type 1 diabetes
- Four times a year if you have type 2 diabetes, you use insulin to manage your diabetes, or you have trouble keeping your blood sugar level within your target range
You may need more frequent A1C tests if your doctor changes your diabetes treatment plan or you begin taking a new diabetes medication.
- A1c and eAG. American Association for Clinical Chemistry. http://www.labtestsonline.org/understanding/analytes/a1c/test.html. Accessed Nov. 7, 2012.
- Malkani S, et al. Implications of using hemoglobin A1C for diagnosing diabetes mellitus. The American Journal of Medicine. 2011;124:395.
- A1C. American Diabetes Association. http://www.diabetes.org/living-with-diabetes/treatment-and-care/blood-glucose-control/a1c/. Accessed Nov. 7, 2012.
- 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.
- The A1C test and diabetes. National Institute of Diabetes and Digestive and Kidney Diseases. http://diabetes.niddk.nih.gov/dm/pubs/A1CTest/. Accessed Nov. 7, 2012.
- How often should A1c and LDLs be checked? American Diabetes Association. http://www.diabetes.org/living-with-diabetes/treatment-and-care/ask-the-expert/ask-the-pharmacist/archives/how-often-should-a1c-and-ldls.html?&print=t. Accessed Nov. 8, 2012.
- Castro RM (expert opinion). Mayo Clinic, Rochester, Minn. Nov. 9, 2012
- American Diabetes Association. Standards of medical care in diabetes — 2013. Diabetes Care. 2013:36:S1.
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