Postprandial hyperglycemia is increasingly recognized as an independent risk factor for cardiovascular disease. Glycemic "spikes" may adversely affect vascular structure and function via multiple mechanisms, including (acutely and/or chronically) oxidative stress, inflammation, low-density lipoprotein oxidation, protein glycation, and procoagulant activity. Postprandial glycemia can be reliably predicted by considering both the amount and type of carbohydrate. In particular, the glycemic index (GI), a measure of postprandial glycemic potency weight for weight of carbohydrate, has provided insights that knowledge of the sugar or starch content has not. In prospective observational studies, dietary GI and/or glycemic load independently predict cardiovascular disease, with relative risk ratios of 1.2 to 1.7 comparing highest and lowest quintiles. In randomized controlled trials in overweight subjects, diets based on low-GI carbohydrates have produced better cardiovascular-related outcomes than conventional low-fat diets. Taken together, the findings suggest that health professionals may be able to improve cardiovascular outcomes by recommending the judicious use of low- GI/glycemic load foods.