Objective - To test the effects of two Mediterranean-diet interventions versus a low-fat diet on incidence of diabetes.
Research Design and Methods - Three-arm randomized trial in 418 nondiabetic subjects aged 55-80 years recruited in one center (PREDIMED-Reus, North-Eastern Spain) of the PREDIMED study, a large nutrition-intervention trial for primary cardiovascular prevention in persons at high cardiovascular risk. Participants were randomized to education on a low-fat diet (control group) or one of two Mediterranean diets, supplemented with either free virgin olive oil (1 liter/week) or nuts (30 g/day). Diets were ad libitum and no advice on physical activity was given. The main outcome was diabetes incidence diagnosed by the 2009 American Diabetes Association criteria.
Results - After a median follow-up of 4.0 years, diabetes incidence was 10.1% (95% confidence interval [CI], 5.1-15.1), 11.0% (5.9-16.1), and 17.9% (11.4-24.4) in the Mediterranean-diet with olive oil group, the Mediterranean-diet with nuts group, and the control group, respectively. Multivariable-adjusted hazard ratios of diabetes were 0.49 (0.25-0.97) and 0.48 (0.24-0.96) in the Mediterranean-diet groups supplemented with olive oil and nuts, respectively, compared to the control group. When pooling the two Mediterranean-diet groups compared to the control group, diabetes incidence was reduced by 52% (27-86). In all study arms, increased adherence to the Mediterranean-diet was inversely associated with diabetes incidence. Diabetes risk reduction occurred in the absence of significant changes in body weight or physical activity.
Conclusion - Mediterranean diets without calorie restriction appear to be effective in the prevention of diabetes in subjects at high cardiovascular risk.
Trial Registration: www.controlled-trials.com Identifier: ISRCTN35739639
- Received July 6, 2010.
- Accepted September 28, 2010.
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