The GI has been tested in 14 long-term studies conducted in Canada, France, the United Kingdom, Sweden, and Australia. In these (mainly crossover) studies of people with diabetes, the only variable in the diet was carbohydrate selection. All study subjects showed improvement of HgA1c, averaging 11%, which is similar to the effect of oral hypoglycemic agents.

A Swedish study found that a low-GI diet improved HbA1c in children with type 1 diabetes, even though the fat content of the diet remained the same. The subjects reported that the low-GI diet was easier to follow than the traditional diabetic diet.

Obesity and being overweight are prevalent throughout the developed nations. Dr. Brand-Miller noted that 15 of 16 studies have shown that low-GI foods are more satiating and more effectively delay the return of hunger than high-GI foods. Studies of the low-GI diet in treating obesity are needed to learn its possible value.

Designing Low-GI Diets

Dr. Brand-Miller described her approach to the design of low-GI diets as "This for That":

• Choose a high-carbohydrate, low-fat diet, particularly low in saturated fat. Use the Food Guide Pyramid as a tool.

   

• Choose 1 low-GI food in place of 1 high-GI food per meal.

   

• Enjoy refined sugars in moderation. Most sugary foods have a lower GI than most starchy foods.

Major design points of the low-GI diet follow:

• Keep it simple.("This for That")

   

• Swap half of the total carbohydrate from high- to low-GI. This produces a 15-unit reduction in overall GI.

   

• Focus on foods that contribute the most CHO, such as bread, breakfast foods, and potatoes. These constitute half of the carbohydrate of the Western diet.

   

• Don't worry about foods that contribute small amounts of CHO, such as carrots, even if they have a high GI.

   

The GI is now being considered for inclusion in nutrition labeling in Australia, and a new GI food symbol recently was registered in Australia and North America. It will be used on food packaged in Australia to flag healthy foods that have been GI tested. Dr. Brand-Miller described another tool under development: a glycemic equivalent exchange, which will be most helpful to those who need to monitor their portion sizes more closely.

In her concluding remarks, Dr. Brand-Miller stated that several major health organizations around the world endorse the GI approach, but the ADA is one of the organizations that has not approved the GI diet as a means of assisting people with diabetes in the management of their disease and health. She said that long-term benefits of low-GI diets have demonstrated improved glucose control, blood lipids, and satiety. Low-GI diets are easy in practice, using the "This for That" approach, and they do not restrict variety as do traditional diabetic diets.