Air Pollution & Diabetes

Diabetes Incidence and Long-Term Exposure to Air Pollution

A cohort study

1. Zorana J. Andersen, PHD¹⇓, 
2. Ole Raaschou-Nielsen, PHD¹,
3. Matthias Ketzel, PHD², 
4. Steen S. Jensen, PHD², 
5. Martin Hvidberg, BS²,
6. Steffen Loft, DMSC³, 
7. Anne Tjønneland, DMSC¹, 
8. Kim Overvad, PHD⁴,⁵and 
9. Mette Sørensen, PHD¹

¹Institute of Cancer Epidemiology, Danish Cancer Society, Copenhagen, Denmark 

²Department of Environmental Science, Aarhus University, Roskilde, Denmark 

³Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen, Denmark. 

⁴Department of Epidemiology, School of Public Health, Aarhus University, Aarhus, Denmark

1. ⁵Department of Cardiology, Centre for Cardiovascular Research, Aalborg Hospital, Aarhus University Hospital, Aalborg, Denmark

1. Abstract

OBJECTIVE Animal and cross-sectional epidemiological studies suggest a link between air pollution and diabetes, whereas the limited prospective data show mixed results. We studied the association between long-term exposure to traffic-related air pollution and incidence of diabetes.

RESEARCH DESIGN AND METHODS We followed 57,053 participants of the Danish Diet, Cancer, and Health cohort in the Danish National Diabetes Register between baseline (1993–1997) and 27 June 2006. We estimated the mean levels of nitrogen dioxide (NO₂) at the residential addresses of the cohort participants since 1971 and modeled the association between NO₂ and diabetes incidence with a Cox regression model, separately for two definitions of diabetes: all cases and a more strict definition where unconfirmed cases were excluded.

RESULTS Over a mean follow-up of 9.7 years of 51,818 eligible subjects, there were 4,040 (7.8%) incident diabetes cases in total and 2,877 (5.5%) with confirmed diagnoses. Air pollution was not associated with all diabetes cases (hazard ratio 1.00 [95% CI 0.97–1.04] per interquartile range of 4.9 μg/m³mean NO₂ levels since 1971), but a borderline statistically significant association was detected with confirmed cases of diabetes (1.04 [1.00–1.08]). Among confirmed diabetes cases, effects were significantly enhanced in nonsmokers (1.12 [1.05–1.20]) and physically active people (1.10 [1.03–1.16]).

CONCLUSIONS Long-term exposure to traffic-related air pollution may contribute to the development of diabetes, especially in individuals with a healthy lifestyle, nonsmokers, and physically active individuals.

• Received June 17, 2011.
• Accepted October 7, 2011.

• © 2011 by the American Diabetes Association.

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