Importance of controlling diabetes early--the concept of metabolic memory, legacy effect and the case for early insulinisation.

Most of the microvascular complications of diabetes are related to the degree and the length of exposure to hyperglycaemia. New data from the follow-up studies of the Diabetes Control and Complications Trial-the Epidemiology of Diabetes Intervention and Complications Study (DCCT-EDIC), and the United Kingdom Prospective Diabetes Study (UKPDS) emphasize the role of glycemic control early in the course of the disorder and its value in prevention of later complications. The phenomenon of ongoing beneficial effects on diabetic complications after a period of improved glycemic control even if followed by a return to usual (often poorer) metabolic control has been described as representing "metabolic memory" by the DCCT/EDIC investigators and as a "legacy effect" by the UKPDS investigators. This article reviews these concepts and explores the role of early use of insulin as a tool to achieve good glycemic control in type 2 diabetes.