The glycemic index can seem like a useful tool for a person with diabetes. However, there are problems with this system. The index does not take into consideration that every body is different and will process food differently. For example, the body will process food in a different way early in the morning than late at night. Also, an individual’s metabolism will react differently depending on the portion size a person eats. Portion size is never addressed in the glycemic index food analysis. Portions are important because eating a large amount of a food with raise blood sugar more than eating a smaller amount.
Another problem with this index is it does not effectively rate mixed foods and its impact on blood sugar. Eating a high glycemic food with a low glycemic food will slow down the rate blood sugar increases from the high glycemic food. For example, a person eats a piece of white bread with peanut butter on it. The white bread is a high glycemic index food but the peanut butter will slow down the rise in blood sugar. Peanut butter is a low glycemic food that contains protein and fat. The index does not effectively account for mixing high and low glycemic index foods.
A third problem with the glycemic index is it does not measure how much carbohydrate in actually in the rated food. For example, a watermelon has a high glycemic index but it is made up of mostly water. It would not affect blood sugar the way a piece of plain white bread would. Consistant carbohydrate intake is very important for people with diabetes. The glycemic index does not address the amount of carbohydrates in the rated foods and this makes it confusing for most people -- and could be potentially harmful for people with diabetes. In light of these concerns, the American Diabetes Association does not recommend the Glycemic index as an effective tool for someone trying to control their blood sugar.
For more information visit http://en.wikipedia.org/wiki/Glycemic_index, http://www.mendosa.com/gi.htm, and https://www.health.harvard.edu/newsweek/Glycemic_index_and_glycemic_load_for_100_foods.htm.
