A prospective study investigating the association between environmental tobacco smoke exposure and the incidence of type 2 diabetes in never smokers

Purpose We studied a cohort of individuals to assess whether intensity of environmental tobacco smoke (ETS) exposure is associated with the incidence of type 2 diabetes. Methods Study subjects were selected from an ongoing population-based cohort of Korea Genome and Epidemiology Study. Participants of the baseline study 10,038 persons within the age range of 40 to 69 years old. Among 4,442 never smokers without prevalent diabetes, 465 type 2 diabetes cases were identified through biennial active follow-ups for a 6-year period. Cox proportional hazard models were used to estimate the hazard ratio (HR) and 95% confidence intervals (CI) after adjustment for covariates. Results The risk of type 2 diabetes was higher in subjects exposed to ETS compared with the nonexposure group (HR = 1.41, 95% CI: 1.1–1.70). Daily exposure to ETS at home increased the risk of type 2 diabetes when compared with the risk level of nonexposure (HR = 1.46, 95% CI: 1.16–1.83). Over 4 hours exposure to ETS at home and in the workplace was associated with increased the risk of type 2 diabetes (HR = 1.96, 95% CI: 1.21–3.19). Conclusions Our study suggests that ETS exposure is a significant risk factor for the development of type 2 diabetes with dose-response relationship.