A glycemic index chart indicates the extent to which foods are able to affect blood sugar and insulin levels, according to Harvard Medical School. A food with a low glycemic index has less impact. Foods are typically compared to glucose, which has a GI of 100.
Glycemic index information helps people with diabetes balance their diets, the American Diabetes Association states. Only foods with carbohydrates have glycemic indexes. Therefore, plain meats and fats have no GI. Low GI foods include most fruits, nonstarchy vegetables, sweet potatoes, oatmeal, legumes, lentils, converted rice and 100 percent stone-ground, whole-wheat bread. Examples of foods high on the index are white bread, instant oatmeal, russet potatoes, pretzels, popcorn, melons and pineapple.