Hemoglobin A1c (HbA1c)
What is HbA1c?
Hemoglobin is the oxygen-carrying pigment that gives blood its red color and is also the predominant protein in red blood cells. About 90% of hemoglobin is hemoglobin A (the "A" stands for adult type). Although one chemical component accounts for 92% of hemoglobin A, approximately 8% of hemoglobin A is made up of minor components that are chemically slightly different. These minor components include hemoglobin A1c, A1b, A1a1, and A1a2. Hemoglobin A1c (HbA1c) is a minor component of hemoglobin to which glucose is bound. HbA1c also is sometimes referred to as glycosylated or glycosylated hemoglobin or glycohemoglobin.
Why measure HbA1c?
In addition to random fasting blood glucose levels, HbA1c levels are routinely measured in the monitoring of people with diabetes. HbA1c levels depend on the blood glucose concentration. That is, the higher the glucose concentration in blood, the higher the level of HbA1c. Levels of HbA1c are not influenced by daily fluctuations in the blood glucose concentration but reflect the average glucose levels over the prior six to eight weeks. Therefore, HbA1c is a useful indicator of how well the blood glucose level has been controlled in the recent past (over two to three months) and may be used to monitor the effects of diet, exercise, and drug therapy on blood glucose in people with diabetes.
In healthy people the HbA1c level is less than 6% of total hemoglobin. Studies have demonstrated that the complications of diabetes can be delayed or prevented if the HbA1c level can be kept below 7%. It is recommended that treatment of diabetes be directed at keeping an indivudual's HbA1c level as close to normal as possible (<6%) without episodes of hypoglycemia (low blood glucose levels).
Medically Reviewed by a Doctor on 7/30/2014
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