Metformin Treatment With or Without Mediterranean Diet for the Prevention of Age-Related Diseases in People With Metabolic Syndrome: The MeMeMe Randomized Trial

OBJECTIVE: The Metformin and Dietary Restriction to Prevent Age-Related Morbid Events in People With Metabolic Syndrome (MeMeMe) trial tested whether 1,700 mg/day metformin (MET) with or without a Mediterranean diet (MedDiet) intervention could reduce the cumulative incidence of major noncommunicable diseases in people with metabolic syndrome. RESEARCH DESIGN AND METHODS: A total of 1,442 participants were randomly assigned to one of four interventions: 1) MET (1,700 mg/day) plus MedDiet intervention (MET+MedDiet); 2) placebo plus MedDiet intervention; 3) MET (1,700 mg/day) alone; and 4) placebo alone. Participants were followed up for 3 years on average. The primary outcome was the cumulative incidence of major noncommunicable diseases (including type 2 diabetes, cardiovascular diseases, and cancer). Secondary outcomes were the incidence of type 2 diabetes and the changing prevalence of metabolic syndrome. RESULTS: The crude incidence of the major noncommunicable diseases was 6.7 cases per 100 person-years in the MET+MedDiet group, 6.9 in the MET alone group, 13.3 in the placebo plus MedDiet group, and 11.3 in the placebo group. The differences were fully explained by the reduction of type 2 diabetes, which was 80% and 92% lower in the MET and MET+MedDiet groups, respectively, compared with placebo. CONCLUSIONS: The use of 1,700 mg/day MET is effective to prevent diabetes in people selected on the basis of metabolic syndrome.