How long-term air pollution and its metal constituents affect type 2 diabetes mellitus prevalence? Results from Wuhan Chronic Disease Cohort

BACKGROUND: Epidemiological evidence linking type 2 diabetes mellitus (T2DM) with air pollution is discrepant and most are restricted to the influences of air-pollutant mass concentration. This study aims to explore the effects of long-term exposure to air pollution and its metal constituents on T2DM prevalence in China. METHODS: We used data on 10,253 adult residents from the baseline survey of Wuhan Chronic Disease Cohort in 2019. Ambient PM(2.5), PM(10) and NO(2) exposure were estimated at residences based on Chinese Air Quality Reanalysis Dataset. Concentrations of 10 metal constituents were measured by 976 PM(2.5) filter samples collected from four monitoring stations. Logistic regression models were employed to examine associations of T2DM prevalence with 3-year mean concentrations of each air pollutant and PM(2.5) metal constituents prior to the baseline investigation. RESULTS: A total of 673 T2DM cases (6.6%) were identified. The 3-year mean exposures to PM(2.5), PM(10) and NO(2) were 50.89 μg/m(3), 82.86 μg/m(3), and 39.79 μg/m(3), respectively. And interquartile range (IQR) of 10 metals in PM(2.5) varied from 0.03 ng/m(3) to 78.30 ng/m(3). For 1 μg/m(3) increment in PM(2.5), PM(10) and NO(2), the odds of T2DM increased by 7.2% (95%CI: 1.026, 1.136), 3.1% (95%CI: 1.013, 1.050), and 2.1% (95%CI: 1.005, 1.038) after adjusting for potential confounders. Cd and Sb in PM(2.5) were significant risk factors to T2DM with odds ratios of 1.350 (95%CI: 1.089, 1.673) and 1.389 (95%CI: 1.164, 1.658) for per IQR increase, respectively. Stratification analyses indicated that males and those aged ≥45 years were more susceptive to long-term air pollution. CONCLUSIONS: Long-term exposure to PM(2.5), PM(10) and NO(2) increased T2DM prevalence in a Wuhan population, especially for men and middle-aged and elderly people. Moreover, T2DM was significantly associated with Cd and Sb in PM(2.5). Further research to validate these results and to clarify the underlying mechanisms is warranted.