Effects of a Mediterranean Eating Plan on the Need for Glucose-Lowering Medications in Participants With Type 2 Diabetes: A Subgroup Analysis of the PREDIMED Trial

OBJECTIVE: To examine the effects of two Mediterranean eating plans (Med-EatPlans) versus a low-fat eating plan on the need for glucose-lowering medications. RESEARCH DESIGN AND METHODS: From the Prevención con Dieta Mediterránea (PREDIMED) trial, we selected 3,230 participants with type 2 diabetes at baseline. These participants were randomly assigned to one of three eating plans: Med-EatPlan supplemented with extra-virgin olive oil (EVOO), Med-EatPlan supplemented with mixed nuts, or a low-fat eating plan (control). In a subgroup (15%), the allocation was done in small clusters instead of using individual randomization, and the clustering effect was taken into account in the statistical analysis. In multivariable time-to-event survival models, we assessed two outcomes: 1) introduction of the first glucose-lowering medication (oral or injectable) among participants on lifestyle management at enrollment and 2) insulin initiation. RESULTS: After a median follow-up of 3.2 years, in multivariable analyses adjusting for baseline characteristics and propensity scores, the hazard ratios (HRs) of starting a first glucose-lowering medication were 0.78 (95% CI 0.62-0.98) for Med-EatPlan + EVOO and 0.89 (0.71-1.12) for Med-EatPlan + nuts, compared with the control eating plan. After a median follow-up of 5.1 years, the adjusted HRs of starting insulin treatment were 0.87 (0.68-1.11) for Med-EatPlan + EVOO and 0.89 (0.69-1.14) for Med-EatPlan + nuts compared with the control eating plan. CONCLUSIONS: Among participants with type 2 diabetes, a Med-EatPlan + EVOO may delay the introduction of new-onset glucose-lowering medications. The Med-EatPlan did not result in a significantly lower need for insulin. The supplemental foods used in the study were donated by Patrimonio Comunal Olivarero and Hojiblanca, Madrid, Spain (EVOO); the California Walnut Commission, Sacramento, CA (walnuts); and Borges SA (almonds) and La Morella Nuts (hazelnuts), Reus, Spain. The PREDIMED trial was supported by Instituto de Salud Carlos III, the official funding agency for biomedical research of the Spanish government, through grants provided to research networks specifically developed for the trial (RTIC RD 06/0045 [coordinator: M.A.M.-G.] and RTIC G03/140 [coordinator: R.E.]). All investigators of the PREDIMED trial belong to CIBER, an initiative of Instituto de Salud Carlos III. The authors also acknowledge grants from the National Institutes of Health Clinical Center (1R01-HL-118264-01 and 1R01-DK-102896), Fondo de Investigación Sanitaria–Fondo Europeo de Desarrollo Regional (PI04/0233, PI05/0976, PI07/0240, PI10/01407, PI10/02658, PI11/00049, PI11/02505, and AGL2010-22319-C03-03), Consejería de Salud Junta de Andalucía (PI0105/2007), and the Generalitat Valenciana, Valencia, Spain (ACOMP/2013/165 and COMP/2013/159).