Can the Glycemic Index (GI) be used as a tool in the prevention and management of Type 2 diabetes?

The large increase in type 2 diabetes (T2DM), the considerable lifetime risk of diabetes and the loss of lifetime call for concerted action to prevent T2DM and its complications. Since diabetes is characterized by abnormal glucose metabolism, the question arises of whether a high intake of carbohydrates that are rapidly absorbed as glucose may increase the risk and worsen the course of T2DM. To quantify the impact of carbohydrates on blood glucose the glycemic index (GI) and the glycemic load (GL) have been applied. The GI of a food is a method of ranking carbohydrate rich foods according to their glycemic responses. GI is defined as the incremental area under the blood glucose curve of 50g carbohydrate of a test food expressed as a percentage of the area of the response to an equivalent amount of a reference food (glucose or white bread). In relation to GI/GL and prevention of T2DM there is insufficient information from observational studies to determine whether a positive association exists or not. Only randomized controlled clinical intervention studies will be able to provide the final answer. From meta-analyses of randomised controlled clinical trials comparing low and high GI diets in the treatment of diabetes it has been found that low GI diets improve the glycemic control. Labeling of foods with GI would be helpful for persons with diabetes, but the usefulness for healthy subjects remains to be clarified. At present it seems premature to introduce GI labeling for the entire population.