Carbohydrate on Cardiovascular Disease Risk Factors and Insulin Sensitivity The OmniCarb Randomized Clinical Trial

IMPORTANCE Foods that have similar carbohydrate content can differ in the amount they raise blood glucose. The effects of this property, called the glycemic index, on risk factors for cardiovascular disease and diabetes are not well understood. OBJECTIVE To determine the effect of glycemic index and amount of total dietary carbohydrate on risk factors for cardiovascular disease and diabetes. DESIGN, SETTING, AND PARTICIPANTS Randomized crossover-controlled feeding trial conducted in research units in academic medical centers, in which 163 overweight adults (systolic blood pressure, 120-159mmHg) were given 4 complete diets that contained all of their meals, snacks, and calorie-containing beverages, each for 5 weeks, and completed at least 2 study diets. The first participant was enrolled April 1, 2008; the last participant finished December 22, 2010. For any pair of the 4 diets, there were 135 to 150 participants contributing at least 1 primary outcomemeasure. INTERVENTIONS (1) A high–glycemic index (65 % on the glucose scale), high-carbohydrate diet (58 % energy); (2) a low–glycemic index (40%), high-carbohydrate diet; (3) a high–glycemic index, low-carbohydrate diet (40 % energy); and (4) a low–glycemic index