The association between dietary patterns and type 2 diabetes: a systematic review and meta-analysis of cohort studies.
Observational studies suggest that dietary pattern intake plays an important role in the development of type 2 diabetes. A meta-analysis was performed of existing cohort studies on the association between dietary patterns and the risk of type 2 diabetes. Pertinent studies were identified by searching MEDLINE, EMBASE, Cumulative Index to Nursing and Allied Health Literature, PROQUEST, MEDNAR and the Joanna Briggs Institute Library of Systematic Reviews, as well as the reference lists of all identified studies up to September 2012. A random-effects meta-analysis was performed to pool relative risk (RR) estimates from individual studies to assess the relationship between dietary pattern intake and the risk of type 2 diabetes. Statistical heterogeneity was assessed using I(2) and sensitivity analyses were conducted. Publication bias was evaluated by visual inspection of funnel plots and was formally assessed using Egger's test. There were fifteen cohort studies that met the inclusion criteria. There was evidence of a reduction in the risk of type 2 diabetes in the highest adherence compared to the lowest adherence to healthy dietary patterns [RR = 0.79, 95% confidence interval (CI) = 0.74-0.86, P < 0.005]. An increase in the risk of type 2 diabetes was evident for the highest adherence compared to the lowest adherence to unhealthy dietary patterns (RR = 1.44, 95% CI = 1.33-1.57, P < 0.005). The results of this systematic review and meta-analysis indicate that dietary patterns may be associated with the risk of type 2 diabetes.