The clinical application of the glycemic index (GI) to the prevention and treatment of chronic diseases is controversial. No evidence exists for the implementation of low-GI diets for a reduction in coronary heart disease (CHD) mortality, events, or morbidity. Observational studies report conflicting evidence on the role of low-GI diets in CHD and risk factors for CHD. Randomized clinical trials report a small reduction in total cholesterol (-6.6 mg/dL) from low-GI diets compared with high-GI diets, but no reduction in other risk factors, such as low-density lipoprotein or high-density lipoprotein cholesterol, triglycerides, fasting glucose, insulin, or body weight. Currently, the research suggests a minimal role for the implementation of low-GI diets in the prevention or treatment of CHD.