A1c, Hemoglobin A1c

The A1c (hemoglobin A1c, glycosylated hemoglobin) test checks the average amount of sugar (glucose) in the blood over the last 2 to 3 months. It does this by measuring the concentration of glycosylated hemoglobin. As glucose circulates in the blood, some of it binds to hemoglobin A. This is the main form of hemoglobin in adults. Hemoglobin is a red protein that carries oxygen in the red blood cells (RBCs). Once the glucose is bound to the hemoglobin A, it remains there for the life of the red blood cell (about 120 days). This combination of glucose and hemoglobin A is called A1c. Increased glucose in the blood, increases the hemoglobin A1c. A1c levels do not change quickly but will shift as RBCs are replaced.

A1c is a valuable test because it enables you to know how your glucose has been controlled over the past 3 months.

  • 5% A1c

  • Estimated Average Glucose mg/dL: 97

  • 6% A1c

  • Estimated Average Glucose mg/dL: 126

  • 7% A1c

  • Estimated Average Glucose mg/dL: 154

  • 8% A1c

  • Estimated Average Glucose mg/dL: 183

  • 9% A1c

  • Estimated Average Glucose mg/dL: 212

  • 10% A1c

  • Estimated Average Glucose mg/dL: 240

  • 11% A1c

  • Estimated Average Glucose mg/dL: 269

  • 12% A1c

  • Estimated Average Glucose mg/dL: 298

The American Diabetes Association (ADA) recommends testing your A1c level 4 times each year if you have type 1 or type 2 diabetes and use insulin; or 2 times each year if you have type 2 diabetes and do not use insulin. When someone is first diagnosed with diabetes or if control is not good, A1c may be ordered more frequently.

PREPARATION FOR TEST

No preparation or fasting is necessary for this blood sample.

NORMAL FINDINGS

  • Adults without diabetes: 2.2 to 4.8%

  • Children without diabetes: 1.8 to 4.0%

  • Good diabetic control: 2.5 to 5.9%

  • Fair diabetic control: 6 to 8%

  • Poor diabetic control: greater than 8%

The values of A1c may be falsely low in pregnancy, in disorders with shortened red blood cell lives, or in sickle cell disease or trait (carrier). The values may be falsely high in disorders with longer red cell lives, or in people with Thallassemia, kidney failure, or iron deficiency anemia.

Ranges for normal findings may vary among different laboratories and hospitals. You should always check with your doctor after having lab work or other tests done to discuss the meaning of your test results and whether your values are considered within normal limits.

MEANING OF TEST

Your caregiver will go over the test results with you and discuss the importance and meaning of your results, as well as treatment options and the need for additional tests if necessary.

If your A1c is greater than 7%, discuss treatment options with your caregiver.

OBTAINING THE TEST RESULTS

It is your responsibility to obtain your test results. Ask the lab or department performing the test when and how you will get your results.