The glycemic index (GI) characterizes the carbohydrates in different foods. It is a better marker of health effects than the sugar-starch or simple-complex sugars distinctions. Healthy foods with a low GI provide an additional benefit over and above that achieved by conventional low-fat foods in the management and prevention of diabetes and pre-diabetes. The GI of a food product cannot be guessed; it must be tested according to the standardized in vivo method. Many whole-grain products have a high GI.