In 1981, Dr. David Jenkins of the University of Toronto came up with a ranking system for carbohydrates based upon how long it takes them to break down into the system. Some carbohydrates break down very slowly and those release glucose gradually into the bloodstream and have a low glycemic index. For people who are diabetes, particularly those who are insulin dependent, a low glycemic index is preferable. These foods allow the insulin or medication to respond better to the blood glucose and allows for the sugars to break down more naturally.