Diets high and low in glycemic index versus high monounsaturated fat diets: effects on glucose and lipid metabolism in NIDDM.

Objective: To examine the relative effects of high and low glycemic index ( GI) carbohydrates, and monounsaturated fats on blood glucose and lipid meta bolism in NIDDM subjects. Subjects: Fourteen male and seven female variably controlled NIDDM subjects recruited by advertisement. Setting: Free living outpatients. Research design: A repeated measures, within-subject design was used such t hat each subject consumed three diets: (a) a high-GI diet (53% CHO - 21% fa t, 63 GI units (glucose = 100)); (b) a low-GI diet (51% CHO - 23% fat, 43 G I units); and (c) a high-mono high-GI diet (42% CHO - 35% fat, 59 GI units) in random order and cross-over fashion for four weeks. Approximately 45% e nergy was provided as key foods which differed in published GI values and s pecifically excluded legumes. Dietary fibre intake was >30 g/d on each diet . At the end of each dietary intervention, we measured fasting plasma lipid s, glucose, insulin, total glycated plasma protein, fructosamine, LDL and H DL particle size as well as 24 h urinary excretion of glucose and C-peptide . Results: HDL-cholesterol was higher on the low-GI and high-mono high-GI die ts compared to the high-GI diet (P < 0.05 for overall diet effect). There w ere no other significant differences in metabolic control between diets, ev en when adjusted for BMI, glucose control or gender. Body weight and satura ted fat intake remained stable between dietary interventions. Conclusion: High-mono high-GI and high-CHO, low-GI diets are superior to hi gh-CHO, high-GI diets with respect to HDL metabolism but no effect was note d on glucose metabolism in variably controlled NIDDM subjects.