A1C is a test that measures a person's average blood glucose level over the past 2 to 3 months.

Also called hemoglobin A1C or glycosylated hemoglobin, the test shows the amount of glucose that sticks to the red blood cell, which is proportional to the amount of glucose in the blood.

References

American Diabetes Association Website. Last accessed on 4/14/06. http://www.diabetes.org/type-1-diabetes/a1c-test.jsp.