Hemoglobin A1C levels in nondiabetics

^{January 2017}

It has been demonstrated that the development of microvascular complications of diabetes mellitus, especially diabetic retinopathy, can be delayed by establishing more strict glycemic control. As a result, methods of monitoring glycemic control by measuring the amount of glucose attached to various proteins in the blood have been developed. Determination of the amount of glucose that becomes attached to red blood cell hemoglobin – the hemoglobin A1C (HbA1C) level – has become well-established.

The attachment of glucose to the hemoglobin molecule is irreversible, is proportional to the amount of plasma glucose, and begins when a new red blood cell enters the circulation. Approximately one percent of red blood cells are destroyed daily, and the average life span of a red blood cell is about 120 days. This means that, at any point in time, the HbA1C level reflects the average blood glucose level over the prior 120 days.

However, the level actually correlates best with the period covering the previous eight to twelve weeks. Since its introduction, HbA1C testing has been found useful not only in determining the level of diabetic control but also, because of efficiency, has become an accepted method for establishing the diagnosis of diabetes mellitus. Hemoglobin A1C levels of 6.5 percent and greater are now considered to be diagnostic for diabetes mellitus.