Association between exposure to ambient fine particulate matter and prevalence of type 2 diabetes in Iran: an ecological study.

: Epidemiological evidence for the link between long-term exposure to air particulate matter (PM2.5) and occurrence of type 2 diabetes (T2D) is limited such that little is known about the effect of PM2.5 exposure and adult T2D prevalence. Thus, the aim of this ecological study is to evaluate the contribution of ambient PM2.5 exposure to the adult T2D prevalence in the large population of Iran. The study was conducted based on Iran's large-scale cross-sectional surveilling non-communicable diseases (NCDs) risk factors (Timpka et al. 2015b). A total of 31,050 participants were enrolled in three sequential processes of study using cluster random sampling. PM2.5 data in the urban area of 31 provinces of Iran were acquired from Tehran Air Quality Control Company (AQCC) and the Department of Environment (DoE) of Iran during 2012-2016. Moreover, major and minor diabetes risk factors were considered; the Pearson correlation and a stepwise regression model were performed to estimate associations between risk factors and diabetes and prediabetes prevalence. The results showed T2D prevalence was more frequent among women (10.61%) than men (9.35%). A weak positive correlation was observed between PM2.5 level and diabetes prevalence with a correlation coefficient of 0.275, although there was no significant association between PM2.5 value and prediabetes prevalence. Moreover, none of the variables included in the regression model could predict the prevalence of diabetes and prediabetes. According to our study results, it can be suggested that investigating the association between PM2.5 exposure and T2D prevalence at individual level may provide a better understanding of PM2.5 exposure and the risk of T2D prevalence.