Redefining the glycemic index for dietary management of postprandial glycemia.

The glycemic index (GI) is a component-referenced index, defined as the effect on blood glucose of glycemic carbohydrate in a food as a percentage of the effect of an equal amount of glucose. GI is not suitable for dietary management of postprandial glycemia because it refers to glycemic carbohydrate, not to food, it is static, i.e., unresponsive to intake, and it is relative in that it can be used appropriately only for equicarbohydrate comparisons. Food values for dietary management, in contrast, must be food-based, intake responsive and sensitive to variations in composition typical of diets. The limitations of GI could be overcome by expanding its definition beyond glycemic carbohydrate, to foods. GI could then be used as a food-referenced index, expressed as glycemic glucose equivalents (GGE)/100 g food, and extrapolated to GGE per common standard measure (CSM) as a value for the glycemic load exerted by familiar food quantities. GI(food) and GGE/CSM would then be expressed as are nutrients in food composition databases, would lie on the same quantity-dependent continuum and could be used with nutrient information to provide a more complete nutritional profile of a food than is provided by nutrients alone. GI would then be a practical adjunct to food composition data, which was its intended role.