Marta Guasch-Ferré, Nerea Becerra-Tomás, Miguel Ruiz-Canela, Dolores Corella, Helmut Schröder, Ramon Estruch, Emilio Ros, Fernando Arós, Enrique Gómez-Gracia, Miquel Fiol, Lluís Serra-Majem, José Lapetra, Josep Basora, Nerea Martín-Calvo, Olga Portoles, Montserrat Fitó, Frank B Hu, Lluís Forga, Jordi Salas-Salvadó

Background: The associations between dietary fat and cardiovascular disease have been evaluated in several studies, but less is known about their influence on the risk of diabetes.Objective: We examined the associations between total fat, subtypes of dietary fat, and food sources rich in saturated fatty acids and the incidence of type 2 diabetes (T2D).Design: A prospective cohort analysis of 3349 individuals who were free of diabetes at baseline but were at high cardiovascular risk from the PREvención con DIeta MEDiterránea (PREDIMED) study was conducted. Detailed dietary information was assessed at baseline and yearly during the follow-up using a food frequency questionnaire. Multivariable Cox proportional hazards models were used to estimate T2D HRs and 95% CIs according to baseline and yearly updated fat intake.Results: We documented 266 incident cases during 4.3 y of follow-up. Baseline saturated and animal fat intake was not associated with the risk of T2D. After multivariable adjustment, participants in the highest quartile of updated intake of saturated and animal fat had a higher risk of diabetes than the lowest quartile (HR: 2.19; 95% CI: 1.28, 3.73; and P-trend = 0.01 compared with HR: 2.00; 95% CI: 1.29, 3.09; and P-trend < 0.01, respectively). In both the Mediterranean diet and control groups, participants in the highest quartile of updated animal fat intake had an ∼2-fold higher risk of T2D than their counterparts in the lowest quartile. The consumption of 1 serving of butter and cheese was associated with a higher risk of diabetes, whereas whole-fat yogurt intake was associated with a lower risk.Conclusions: In a Mediterranean trial focused on dietary fat interventions, baseline intake of saturated and animal fat was not associated with T2D incidence, but the yearly updated intake of saturated and animal fat was associated with a higher risk of T2D. Cheese and butter intake was associated with a higher risk of T2D, whereas whole-fat yogurt intake was associated with a lower risk of T2D. This trial was registered at www.isrctn.com as ISRCTN35739639.