The 3 R's of Glycemic Index: Recommendations, Research, and the Real World

Abstract

T he ability to achieve optimal glycemic control in diabetes management is highly influenced by food intake. The initial focus for nutrition education messages is to aim for consistency in both type and quantity of carbohydrates consumed. However, research in the past decade has acknowledged that not all carbohydrates effect blood glucose levels in the same way. One of the methods for evaluating this effect is known as the glycemic index (GI). Using the GI in meal planning can improve diabetes control and other health parameters. Understanding the benefits of the GI and how one can implement it into the diet, allows health care practitioners to educate patients about its use. This article will define GI; highlight key recommendations regarding the use of GI scales; summarize recent research related to the impact of choosing lower-GI foods on diabetes control, lipids, and weight; and conclude with some practical, real-world tips for using the GI when counseling patients. The GI is a ranking system that indicates how quickly a carbohydrate food raises blood glucose. This is determined by measuring the area under the curve in the 2 hours after the consumption of a test food. These values are then compared to the area under the curve 2 hours after the consumption of a similar weight of glucose or bread. Foods ranked < 55 are considered to have a low GI. Low-GI foods include many fruits and vegetables, legumes, whole grains, and dairy products. Foods with a ranking between 56 and 75 are considered to have a moderate GI. High-GI foods, those with a ranking between 76 and 100, often include highly processed and refined carbohydrates such as instant oatmeal, white bread, and cornflakes (Table 1). Although the GI ranking compares standard carbohydrate portions (usually 25 or 50 g), the amount of …