Comparison of the effects of a monounsaturated fat diet and a high carbohydrate diet on cardiovascular risk factors in first degree relatives to type-2 diabetic subjects

Objective: Recent studies have demonstrated beneficial metabolic effects of dietary monounsaturated fatty acids (MUFA) in Type-2 diabetes mellitus (Type-2 DM). The question arises if dietary MUFA also has desirable effects on risk markers in subjects with high risk of developing Typed DM. Setting: University department of endocrinology. Subjects: Sixteen healthy, first-degree relatives (six men, 10 women, age (mean +/- s.d.): 35 +/- 2 years) with normal oral glucose tolerance tests. Interventions: Randomised study with two 4-week treatment periods with either a carbohydrate-rich (CHO) diet (55 E% carbohydrate, 30 E% fat, 15 E% protein) or a diet rich in olive oil [MUFA 40 E% fat (25 E% as MUFA), 45 E% carbohydrate, 15 E% protein]. The periods were divided by a 4-week wash-out period. Results: Similar lowering effects on total cholesterol, low density lipoprotein (LDL)-cholesterol, triglyceride and apoB levels were seen after the two diets. Slightly higher levels of high-density lipoprotein (HDL)cholesterol (1.4 +/- 0.4 vs 1.3 +/- 0.4 mmol/l, P < 0.0001) and apoA-1 (1.2 +/- 0.3 vs 1.1 +/- 0.3 mmol/l, P < 0.05) were found in the MUFA-diet. Furthermore, the insulin sensitivity, as assessed by Bergman's minimal model, and the first response insulin areas were similar, as were the 24-h blood pressures and the von Willebrand Factor (VWF) levels. Conclusions: Isocaloric diets rich in MUFA or rich in carbohydrate, respectively, seem to have similar effects on cardiovascular risk factors in persons at high risk of developing Type-2 DM. A potential risk, however, on body weight of high-fat diets should be kept in mind.