A1C--frequently asked questions.

BACKGROUND Routine clinical measurements of glycated haemoglobin first became available during the early 1970s and are now accepted as the standard for estimated overall glycaemic exposure and risk of microvascular complications in diabetes. OBJECTIVE This article attempts to answer frequently asked questions concerning A1C, and provide guidance on how to make best use of A1C measurements in clinical practice. DISCUSSION Blood glucose gives immediate day-to-day information and A1C usually gives a reliable estimate of the average glycaemic exposure over the past 6-8 weeks. Both are important components of glycaemic monitoring. Discrepancies between these two estimates of glycaemia can usually be resolved by checking blood glucose and A1C techniques. Target A1C is less than 7%, but encouraging patients to aim slightly lower (eg. by 0.5%) on A1C can result in significant reduction in complication risk. There is a clear relationship between glycaemic control reflected by A1C and the progression of microvascular complications in both type 1 and type 2 diabetes.