Glycemic Index, Obesity, and Diabetes

Abstract

Prescribing diets to treat obese patients and to prevent type 2 diabetes poses a challenge to clinicians. Overemphasis on carbohydrate-to-fat ratio, with insufficient attention directed toward diet quality, may partially explain disappointing outcomes with available approaches. The glycemic index (GI) is an alternative system for classifying carbohydrate-containing foods according to postprandial blood glucose responses to portions containing a standard amount of available carbohydrate, thereby providing a measure of carbohydrate quality. Because GI is based on standardized portions, glycemic load (GL; product of GI and carbohydrate amount) values are used to describe how portions differing in both quality and quantity of carbohydrate affect postprandial glycemia. Plausible physiologic mechanisms link high-GI or -GL meals with disease processes. Selecting carbohydrate sources to reduce dietary GI—either without altering the contribution of carbohydrate to total energy intake or in combination with a moderate decrease in carbohydrate consumption— is a promising weight management strategy that can be implemented using a pragmatic approach.