Associations between air pollution indicators and prevalent and incident diabetes in an African American cohort, the Jackson Heart Study.

BACKGROUND

Diabetes is especially prevalent among African Americans. Prior studies suggest that long-term exposure to ambient air pollution may be associated with greater incidence of diabetes, but results remain heterogeneous. Few studies have included large numbers of African Americans.

METHODS

We assessed diabetes status and concentrations of 1- and 3-year fine particulate matter (PM) and ozone (O) among African American participants of the Jackson Heart Study at visits 1 (2000-2004, N = 5128) and 2 (2005-2008, N = 2839). We used mixed-effect modified Poisson regression to estimate risk ratios (RRs) and 95% confidence intervals (CIs) of incidence of diabetes by visit 2 and prevalence ratios (PRs) of the association between air pollution exposure and prevalent diabetes at visits 1 and 2. We adjusted for potential confounding by patient characteristics, as well as inverse probability weights of diabetes at visit 2, accounting for clustering by census tract.

RESULTS

We observed associations between incident diabetes and interquartile range increase in 1-year O (RR 1.34, 95% CI = 1.11, 1.61) and 3-year O (RR 0.88, 95% CI = 0.76, 1.02). We observed associations between prevalent diabetes and 1-year PM (PR 1.08, 95% CI = 1.00, 1.17), 1-year O (PR 1.18, 95% CI = 1.10, 1.27), and 3-year O (PR 0.95, 95% CI = 0.90, 1.01) at visit 2.

CONCLUSIONS

Our results provide some evidence of positive associations between indicators of long-term PM and O exposure and diabetes. This study is particularly relevant to African Americans, who have higher prevalence of diabetes but relatively few studies of environmental pollution risk factors.