The numbers on a diabetic glycemic index chart indicate the degree to which various types of food containing carbohydrates raise a person's blood glucose level, reports the American Diabetes Association. Foods with low numbers do not raise blood glucose as much as foods with high numbers do. Although glycemic index, of GI, values of food are useful in helping diabetics make meal plans, other factors are important as well.
Different types of food can have the same carbohydrate counts but different numbers on a glycemic index chart, because the glycemic index number gives an indication of how quickly the carbohydrates in food convert into glucose, explains WebMD. For instance, stone-ground whole wheat bread has a low glycemic index number, normal whole wheat bread has a medium number, and white bread has a high number, according to the American Diabetes Association. The amount of fiber and fat a food contains affects its glycemic index number. Other factors that impact the glycemic index of a food include its ripeness, amount of processing and method of cooking.
Using a glycemic index chart alone is insufficient in planning a diabetic diet, advises the American Diabetes Association. Glycemic index numbers do not take the size of portions into account. Additionally, glycemic index levels change when foods are combined. Some foods with low glycemic index numbers are also low in nutritional value. Carbohydrate counting combined with the use of a glycemic index chart is generally a more efficient way of managing blood glucose levels.