BACKGROUND: Evidence for the association between environmental tobacco smoke (ETS) exposure and the risk of type 2 diabetes mellitus (T2DM) is limited. The aim of this study was to investigate this association in female never-smokers. METHODS: We analyzed 28 177 female participants of the China Kadoorie Biobank (CKB) in Suzhou area, who were never-smokers without diabetes. ETS exposure was defined as exposing to other people's tobacco smoke either at home, workplace or in public places at least 1 day/week. Cox proportional hazard regression models were used to assess the association between ETS exposure and incident T2DM, according to the frequency and duration of ETS exposure, respectively. RESULTS: A total of 774 incident cases of T2DM were identified during a median 7.3 years follow-up. Compared with the no ETS exposure, hazard ratios (95% confidence intervals) for all ETS exposure, the daily and ≥14h/week ETS exposure were 1.17 (1.00-1.37), 1.23 (1.04-1.46) and 1.25 (1.03-1.53), respectively. Moreover, a positive dose-response relationship was observed between ETS exposure level and T2DM (all P<0.05 for trend). CONCLUSIONS: This prospective study suggested that ETS exposure increased the risk of T2DM incidence with dose-response relationship in female never-smokers. Thus, reducing ETS exposure may benefit in decreasing the burden of T2DM in Chinese females. This article is protected by copyright. All rights reserved.
cohort study, environmental tobacco smoke, type 2 diabetes