Glucose assessment requires fasting, has poor preanalytic stability, and is not standardized concentrations are acutely altered by a number of factors and measurement can vary depending on sample type (e.g., plasma or whole blood) and source (e.g., capillary, venous, interstitial). HbA 1c has several advantages over glucose. HbA 1c was rapidly adopted for monitoring glucose control and is now recommended for the diagnosis of diabetes. The discovery that HbA 1c was a valid and reliable measure of average glucose exposure was one of the most important advances in diabetes care.
