Glycated haemoglobin (HbA1c) has a particular clinical interest in diabetes mellitus. Measurement of glycated haemoglobin is a clinically useful means of assessing glycemic control in diabetics. GHb values reflect blood glucose levels over the circulatory half-life of the erythrocyte and correlate significantly with mean blood glucose levels during that time.Therefore, measurement of glycated haemoglobin provides a means, independent of multiple measurements such as patient records of self-monitored blood glucose, for assessing the overall efficacy of therapy.There is significant evidence that maintaining good glycemic control has a positive impact on reducing the development of the long-term complications of diabetes.