Measurement of hemoglobin A1c: Analytical principles and their significance in clinical decision making

Appropriate care and monitoring of the condition of patients with diabetes is indispensable from the regular measurement of hemoglobin A1c levels. Under well defined criteria hemoglobin A1c levels may also support the diagnosis of diabetes. This review provides a short description of the major principles of methods used for hemoglobin A1c determination and it reviews conditions interfering with the results. It also presents cut-off values for therapeutic decision making. As the results of world-wide efforts for standardization of hemoglobin A1c values obtained with different tests in different laboratories, the hemoglobin A1c results are comparable and can be used for clinical decisions. However, hemoglobin A1c should be considered with a particular caution in patients with hemoglobinopathies and in those with conditions affecting the average life-time of red cells