Association between Adherence to the Mediterranean Diet and Risk of Type 2 Diabetes: An Updated Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies

Abstract

Despite earlier meta-analyses on the association between adherences to Mediterranean diet (MD) and risk of diabetes, there is no comprehensive and updated study assessing this issue. Furthermore, no earlier study has examined the nonlinear dose-response relationship between consumption of Mediterranean diet and risk of diabetes. The current systematic review and meta-analysis was done to investigate the linear and non-linear dose-response relationship between Mediterranean diet and incidence of diabetes. Using relevant keywords, electronic searches for prospective studies were conducted in ISI Web of Science, PubMed, and Scopus until January 2022. The reported hazard ratios or odds ratios in the primary studies were regarded as risk ratios (RRs). The overall effect was calculated using a random-effects model that accounts for between-study variability. The potential non-linear dose-response associations were tested using a two-stage hierarchical regression model. Based on 16 prospective studies (with 17 effect sizes), we found that the greatest adherence to the Mediterranean diet was significantly associated with a reduced risk of diabetes (Pooled RR: 0.83; 95 CI: 0.77-0.90; I2 =79, P≤ 0.001). Based on linear dose-response analysis, each 1-score rise in the Mediterranean diet score was associated with a 3 decreased risk of diabetes (HR = 0.97; 95 CI: 0.96-0.98, P< 0.001). A nonlinear relationship (P nonlinearity = 0.001) was also observed between Mediterranean diet score and risk of type 2 diabetes. Even modest adherence to the Mediterranean diet was linked to a decreased incidence of type 2 diabetes.