A diabetic exchange chart works by listing the amount of a food that is equal to approximately 15 grams of carbohydrate, according to the University of California at San Francisco. Diabetics use these charts to plan their meals while remaining within the allowable number of carbohydrates.
Diabetic educators and nutritionists often recommend that patients use the chart in planning both meals and snacks for the day, reports Mayo Clinic. The quantity of food for each choice on the chart has about the same number of carbohydrates, fats and proteins. With the chart, the diabetic quickly learns that an ear of corn or 1/3 cup of pasta both equal one starch choice.
Some diabetics use a glycemic index chart instead of the exchange chart, according to Mayo Clinic. The glycemic index is a measure of a food's impact on the blood sugar levels. White rice or bread provides a quickly absorbed sugar that causes blood glucose levels to spike. Complex carbohydrates, with a lower glycemic index, take longer to digest and prevent these spikes.
The Create Your Plate method for diabetics eliminates the use of charts by filling the plate primarily with nonstarchy vegetables, accented by starches and meats, according to the American Diabetes Association. It offers a different way to eat while maintaining blood sugar levels.