Mechanisms in endocrinology: Main air pollutants and diabetes-associated mortality: A systematic review and meta-analysis

Abstract

Objective: Exposure to high levels of air pollutants may be linked to diabetes-associated mortality, but the associations remain unclear. To assess the associations between main air pollutants and diabetes-associated mortality, a systematic review and meta-analysis was performed. Methods: PubMed, Embase and Web of Science were searched for studies investigating the associations between increments in gaseous (nitrogen dioxide (NO2), sulphur dioxide, ozone (O3) and carbon monoxide) and particulate matter (PM; diameter <2.5 μm (PM2.5) or <10 μm (PM10)) air pollutants and diabetes-associated mortality. Using a random-effects model, relative risks (RRs) and 95% CIs were calculated per interquartile range (IQR) increment or per 10 μg/m3 increment in pollutant concentrations. Results: Out of 925 identified articles, 36 were reviewed in depth and 12 studies from 13 articles satisfying the inclusion criteria (five time-series, five case-crossovers and two cohorts) were finally included. Increased risk of diabetes-associated mortality was associated with higher levels of PM2.5 (per 10 μg/m3: RR=1.123, 95% CI 1.036-1.217, P=0.005, I2=96.1%), PM10 (per 10 μg/m3: RR=1.008, 95% CI 1.004-1.013, P<0.001, I2=0%), NO2 (per 10 μg/m3: RR=1.024, 95% CI 1.007-1.041, P=0.006, I2=49.7%) and O3 (per IQR increment: RR=1.065, 95% CI 1.017-1.115, P=0.007, I2=0.0%). No obvious risk of publication bias was observed. Conclusions: Exposure to high levels of air pollutants is significantly associated with an increased risk of diabetes-associated mortality.