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The glycolated hemoglobin test (A1c, also called hemoglobin A1c or the glycosylated hemoglobin test) is an important blood test to diagnose diabetes or determine control of your diabetes. It provides an average blood glucose measurement over the past six to twelve weeks and is used in conjunction with home glucose monitoring to make treatment adjustments.

The normal range for the A1c test is between 4 percent and 6 percent for people without diabetes. The ideal range for people with diabetes is generally less than 7 percent. For diagnostic purposes, two separate A1c tests at 6.5 percent are positive for diabetes.

People with diabetes who are treated with insulin should have this test four times a year (every 3 months). The test may be needed more frequently when your diabetes is not well-controlled. However, the test should be performed no more often than every six weeks. Those who are not treated with insulin should have this test every four to six months.

If your A1c is this: Your average mean daily plasma blood sugar is around this (mg/dl):
12.0% 298 (240-347)
11.0% 269 (217-314)
10.0% 240 (193-282)
9.0% 212 (170-249)
8.0% 183 (147-217)
7.0% 154 (123-185)
6.0% 126 (100-152)
5.0% 97 (76-120)


  • American Association for Clinical Chemistry. A1c Accessed 1/14/2015.
  • National Diabetes Education Program. Know Your Blood Sugar Numbers Accessed 1/14/2015.
  • American Diabetes Association. A1c and eAG Accessed 1/14/2015.
  • Masharani U. Diabetes Mellitus & Hypoglycemia In: Papadakis MA, McPhee SJ, Rabow MW. eds. Current Medical Diagnosis & Treatment 2015. New York, NY: McGraw-Hill; 2014. Accessed 1/14/2015.

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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 1/29/2013...#9731