Association between long-term exposure to ambient air pollution and diabetes mortality in the US

Recent mechanistic and epidemiological evidence implicates air pollution as a potential risk factor for diabetes; however, mortality risks have not been evaluated in a large US cohort assessing exposures to multiple pollutants with detailed consideration of personal risk factors for diabetes. We assessed the effects of long-term ambient air pollution exposures on diabetes mortality in the NIH-AARP Diet and Health Study, a cohort of approximately a half million subjects across the contiguous U.S. The cohort, with a follow-up period between 1995 and 2011, was linked to residential census tract estimates for annual mean concentration levels of PM2.5, NO2, and O3. Associations between the air pollutants and the risk of diabetes mortality (N = 3598) were evaluated using multivariate Cox proportional hazards models adjusted for both individual-level and census-level contextual covariates. Diabetes mortality was significantly associated with increasing levels of both PM2.5 (HR = 1.19; 95% CI: 1.03–1.39 per 10 μg/m3) and NO2 (HR = 1.09; 95% CI: 1.01–1.18 per 10 ppb). The strength of the relationship was robust to alternate exposure assessments and model specifications. We also observed significant effect modification, with elevated mortality risks observed among those with higher BMI and lower levels of fruit consumption. We found that long-term exposure to PM2.5 and NO2, but not O3, is related to increased risk of diabetes mortality in the U.S, with attenuation of adverse effects by lower BMI and higher fruit consumption, suggesting that air pollution is involved in the etiology and/or control of diabetes. •The NIH-AARP Diet and Health Study was linked with latest prediction models for PM2.5, NO2, and O3.•Long-term exposures to PM2.5 and NO2 are significantly associated with elevated diabetes mortality risk.•The associations were significantly modified by BMI and total fruit consumption.