Obstructive sleep apnoea and the risk of type 2 diabetes: A meta-analysis of prospective cohort studies

Background and objective: There has been increasing recognition that obstructive sleep apnoea (OSA) is associated with incident type 2 diabetes. The aim of this study was to assess the association between the severity of OSA and the risk of type 2 diabetes by performing a meta-analysis of all available prospective cohort studies. Methods: A search was conducted of the PubMed, EMBASE, CINAHL and ISI Web of Knowledge databases through March 2012 to identify studies linking OSA with the risk of diabetes. Only prospective cohort studies, in which the presence of OSA was confirmed by objective measurements, were included. Fixed and random effects models were used to calculate pooled relative risks (RR). Results: This meta-analysis of six prospective cohort studies including a total of 5953 participants, with follow-up periods of 2.7-16 years, and 332 incident cases of type 2 diabetes, showed that moderate-severe OSA was associated with a greater risk of diabetes (RR 1.63; 95% confidence interval (CI): 1.09-2.45), as compared with the absence of OSA. Sensitivity analyses yielded similar results. For subjects with mild OSA, as compared with those without OSA, the pooled RR of developing type 2 diabetes was 1.22 (95% CI: 0.91-1.63). Conclusions: This meta-analysis indicates that moderate-severe OSA is associated with an increased risk of type 2 diabetes, and this appears to be an independent risk factor for the development of diabetes.