Assessment of glycemia in diabetes mellitus: Hemoglobin A₁c

The monitoring of glycemia is an essential component of diabetes care. It may be divided into self-monitoring of blood glucose (SMBG), which measures the immediate level of glycemia, and measurement of hemoglobin A₁c (HbA₁c), which reflects longer-term glycemia. SMBG was discussed in an earlier review. HbA₁c is a measure of erythrocyte hemoglobin glycation, and since erythrocytes have about a 120 day life span, HbA ₁c reflects mean glycemia for the previous 3 months (weighted to the most recent month). There are several conditions that confound the HbA ₁c measurement such as hemolytic anaemia (lowers HbA₁c) or aplastic anaemia (raises it), but in most circumstances HbA₁c is a valid index of glycemia. The recommendation is to measure HbA₁c every 3-6 months, and treat to a target level of <7%. If these recommendations were successfully followed in most people with diabetes, long-term complications, especially microvascular complications, would be markedly reduced.