Reduction in the Incidence of Type 2-Diabetes with the Mediterranean Diet: Results of the PREDIMED-Reus Nutrition Intervention Randomized Trial

  1. For the PREDIMED Study investigators
  1. From the Human Nutrition Unit, Hospital Universitari de Sant Joan, Departament de Bioquímica i Biotecnologia, IISPV, Universitat Rovira i Virgili, Reus (J.S., M.B., N.B., N.I., J.B.); Department of Preventive Medicine and Public Health, University of Navarra, Pamplona (M.A.M.); SAP Reus-Altebrat, Institut Català de la Salut, Reus (J.B.); Department of Internal Medicine, Institut d'Investigacions Biomèdiques August Pi Sunyer (IDIBAPS), Hospital Clínic, Barcelona (R.E.); Cardiovascular Risk and Nutrition Research Group, Institut Municipal d'Investigació Mèdica (IMIM), Barcelona (M.I.C); Department of Preventive Medicine and Public Health, University of Valencia, Valencia (D.C); Department of Cardiology, University Hospital Txagorritxu, Vitoria (F.A.); Instituto de la Grasa, CSIC, Sevilla (V.R); Lipid Clinic, Service of Endocrinology and Nutrition, IDIBAPS, Hospital Clínic, Barcelona (E.R.); and CIBER Fisiopatologia de la Obesidad y Nutrición (CIBERObn), Instituto de Salud Carlos III, Spain (J.S.; M.B., N.B., M.A.M., N.I., J.B., R.E., M.I.C., D.C., F.A., E.R.)


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: Identifier: ISRCTN35739639

  • Received July 6, 2010.
  • Accepted September 28, 2010.

This Article

  1. Diabetes Care
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