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A1C – A Test of Your Average Blood Glucose Levels

If you have diabetes, your doctor may use the A1C test to track how well your blood sugar is being controlled.   This test is also sometimes called glycated hemoglobin, glycosylated hemoglobin, hemoglobin A1C, or HbA1c.

The A1C test is a standard blood test used for an initial diagnosis of all types of diabetes.  Diabetes is a condition that results in too much sugar or glucose in your blood.  Red blood cells contain a protein called hemoglobin which carries oxygen from the lungs to the cells in the body.  When there is extra glucose in the blood, the glucose is able to get inside the red blood cells and bond to the hemoglobin.  Once there, the glucose stays in the red blood cell through the life of that cell, which is between two and three months.

By measuring how much glucose is in the red blood cells, the A1C test is able to give an average blood glucose level over a two to three month span.  Other types of blood tests, such as the daily test patients do at home, can only measure how much sugar is in the blood at the time the test is done.  This number can fluctuate significantly throughout the day depending on foods eaten, exercise, and how much insulin was injected or produced by the body.   The A1C test provides valuable information for managing diabetes including:

  • Confirming the results of other, more time-specific test results such as home testing.
  • Judging whether a treatment program is working or not.
  • Showing how healthy food choices and exercises can have long-term results in controlling diabetes.

In general, patients who have type 2 diabetes should have the A1C test done twice a year if blood sugar levels are well managed without injecting insulin.  Type 1 diabetics should have the test done three to four times a year to confirm that the treatment program is maintaining a good average sugar level.  Type 2 diabetics who inject insulin should also have the test three to four times a year.

These are the general categories of A1C test results:

  • 4.5 to 6 percent – normal, no diabetes
  • 5.7 to 6.4 percent – may be considered pre-diabetes or at risk of diabetes depending on other risk factors
  • Over 6 percent – diabetes

Someone whose diabetes has been out of control for some time may have a reading of 9 percent or more.  An average A1C result of 7 is often the goal for diabetics whose sugar levels are well-controlled.

The A1C test is a valuable tool for patients and doctors to determine how well blood sugar is being controlled over a span of time.  It is important to note that it cannot replace home blood glucose testing, and it cannot help determine how much insulin should be given at a particular time.


Denise DeWitt is a freelance writer for




Mayo Clinic. A1C test. Web. February 13, 2012.



American Diabetes Assocation. Living With Diabetes: A1C. Web. February 13, 2012.



National Diabetes Information Clearinghouse. The A1C Test and Diabetes. Web. February 13, 2012.


Denise DeWitt is a freelance writer for


Reviewed on February 15, 2012

by Maryann Gromisch, RN

Edited by Jody Smith





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