Main air pollutants and diabetes-associated mortality: a systematic review and meta-analysis.

Abstract

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. 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. 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. Exposure to high levels of air pollutants is significantly associated with an increased risk of diabetes-associated mortality.