Print-friendly version
Email this article

Update

As of 2002, the American Diabetes Association (ADA) Clinical Practice Guidelines document that the ADA has adopted the common term of A1C to replace HbA1c. This basic article has incorporated this change.

What is Hemoglobin A1c (A1C)?

Hemoglobin is a protein found in your red blood cells. It is responsible for carrying oxygen in the red blood cells to the rest of your body, for energy. The "life" of red blood cells is about two to three months. The body continuously makes new red blood cells to replace those that die.

Sugar in your blood can bind to hemoglobin, and the more sugar in the blood, the more binds to hemoglobin. Thus, the A1C test measures the average blood sugar levels over the two to three month life span of the red blood cells.

Based on a "normal" blood glucose range, there is also a "normal" A1C range. This range is typically stated to be 4% to 6%, meaning that of all the hemoglobin in the red blood cells, 4 to 6% has sugar bound to it. If the blood sugar is higher than normal for a period of time, say one to four weeks, then more sugar will be bound to hemoglobin, and the A1C value will increase. Notice that the blood sugar needs to be elevated for a period of time before the A1C value will increase. Therefore, the A1C test indicates how well controlled your blood sugar is over the "long-term".

We have learned that keeping your blood sugar in the desired range reduces the risk of complications due to diabetes. This includes decreasing the risk of eye disease, kidney disease, nerve disease and heart disease. Measuring your blood glucose values regularly throughout the day, and checking your A1C every three months will help guide you in your therapy.

1 2 3 4 Next Page