OBJECTIVE To compare the influence on blood pressure, glucose, and lipid levels of a diet rich in monounsaturated fatty acids with an isocaloric, highcarbohydrate diet in 15 NIDDM subjects.

RESEARCH DESIGN AND METHODS A crossover design with diet interventions and wash-out periods of 3 wk was applied. The patients were randomly assigned to a 3-wk treatment with a high-carbohydrate diet containing 50% of energy as carbohydrate and 30% of energy as fat (10% of energy as monounsaturated fatty acids) or an isocaloric diet with 30% of energy as carbohydrate and 50% of energy as fat (30% of energy as monounsaturated fatty acids). On the last day of the two diets, 24-h ambulatory blood pressure was measured and day profiles of glucose, hormones, and lipids were performed to a test menu rich in carbohydrates.

RESULTS The diet rich in monounsaturated fat reduced daytime systolic (131 ± 3 vs. 137 ± 3 mmHg, P < 0.04) and 24-h systolic blood pressure (126 ± 8 vs. 130 ± 10 mmHg, P < 0.03) as well as daytime diastolic (78 ± 2 vs. 84 ± 2 mmHg, P < 0.02) and diurnal diastolic blood pressure (75 ± 6 vs. 78 ± 5 mmHg, P < 0.03) as compared with the high-carbohydrate diet. Evidence of lowered blood glucose levels on the high-monounsaturated diet compared with the highcarbohydrate diet were found with lower fasting blood glucose (6.1 ± 0.3 vs. 6.8 ± 0.5 mM, P < 0.05), lower average blood glucose levels (7.4 ± 0.5 vs. 8.2 ± 0.6 mM, P < 0.04), and peak blood glucose responses (9.9 ± 0.6 vs. 11.3 ± 0.7 mM, P < 0.02). The two diets had the same impact on lipid levels.

CONCLUSIONS A diet rich in monounsaturated fat has beneficial effects on blood pressure and glucose metabolism, whereas no adverse effects on lipid composition in NIDDM subjects is detected.