Impact of PM2.5 exposure in old age and its interactive effect with smoking on incidence of diabetes

To determine the impact of PM2.5 exposure in old age and its interactive effect with smoking on incident diabetes. A total of 2766 participants aged ≥60 years in China were interviewed at baseline for disease risk factors in 2001–03 and were then followed up for 10 years to document incident diabetes. They were assessed for daily PM2.5 exposure in 2005. Multivariate Cox regression models were used to examine the association of PM2.5 exposure with incident diabetes and interactive effect between PM2.5 and smoking on incident diabetes. During the cohort follow-up, 176 participants developed diabetes. The incidence of diabetes increased with PM2.5 exposure; the multiple-adjusted hazard ratio (HR) of diabetes was 2.27 (95 % CI 1.36–3.77) in participants with PM2.5 at ≥62.0 μg/m3 compared to those at