Effect of long-term exposure to PM2.5 on the risk of type 2 diabetes and arthritis in type 2 diabetes patients: Evidence from a national cohort in China

Background: It remains unclear whether type 2 diabetes and the complication of arthritis are causally related to the PM2.5 pollutant. Therefore, we aimed to investigate the associations of long-term PM2.5 exposure with type 2 diabetes and with arthritis in type 2 diabetes patients.Materials and methods: This study used data from the China Health and Retirement Longitudinal Survey (CHARLS) implemented during 2011-2018. The associations were analyzed by Cox proportional hazards regression models, and the population-attributable fraction (PAF) was calculated to assess the burden of type 2 diabetes and arthritis-attributable to PM2.5.Results: A total of 21,075 participants were finally included, with 19,121 analyzed for PM2.5 and type 2 diabetes risk and 12,427 analyzed for PM2.5 and arthritis risk, of which 1,382 with newly-diagnosed type 2 diabetes and 1,328 with arthritis during the follow-up. Overall, each 10 mu g/m3 increment in PM2.5 concentration was significantly associated with an increase in the risk of type 2 diabetes (HR = 1.26, 95 %CI1.22 to 1.31), and the PAF of type 2 diabetes attributable to PM2.5 was 13.54 %. In type 2 diabetes patients, each 10 mu g/m3 increment in PM2.5 exposure was associated with an increase in arthritis (HR = 1.42, 95 %CI: 1.28 to 1.57), and the asso-ciation was significantly greater than that (H = 1.23, 95 %CI: 1.19 to 1.28) in adults without type 2 diabetes. The PAFs of arthritis-attributable to PM2.5 in participants with and without type 2 diabetes were 18.54 % and 10.69 %, respectively.Conclusion: Long-term exposure to PM2.5 may increase the risk of type 2 diabetes and make type 2 diabetes patients susceptible to arthritis.