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

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. 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. 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 μg/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 μg/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 association 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. Long-term exposure to PM2.5 may increase the risk of type 2 diabetes and make type 2 diabetes patients susceptible to arthritis.