Comparison of low glycemic index high carbohydrate, high glycemic index high carbohydrate and monounsaturated fat-enriched diets on insulin sensitivity in the treatment of impaired glucose tolerance

grantor: University of TorontoThe purpose of this thesis was to compare the effects of altering the source and amount of carbohydrate on insulin sensitivity (SI) and mean insulin levels in subjects with impaired glucose tolerance (IGT). IGT subjects (n = 34) were randomized to either a high-glycemic-index-high-carbohydrate (high-GI), low-glycemic-index-high-carbohydrate (low-GI) or high-monounsaturated-fat-low-carbohydrate diet (MUFA) for four months using a randomized parallel design. No significant difference in SI was found on any of the dietary treatments. The glucose disposition index (SI X AIRglu) improved by 56% on the low-GI group compared to a 16% reduction in the MUFA group (p = 0.01). Free fatty acid levels decreased significantly by 25% (p = 0.027) on the low-GI diet, but not on the other diets. There were no differences in fasting blood lipids, glucose, HbA1c or insulin. If these changes were sustained (over the long-term), a low-glycemic-index-high-carbohydrate diet would be expected to reduce the rate of progression of IGT to diabetes.M.Sc