Are Particulate Matter Exposures Associated with Risk of Type 2 Diabetes?

Abstract

BackgroundAlthough studies have found that diabetes mellitus (DM) modifies the impact of exposures from air pollution on cardiovascular outcomes, information is limited regarding DM as an air pollution-associated outcome.ObjectivesUsing two prospective cohorts, the Nurses’ Health Study (NHS) and the Health Professionals Follow-Up Study (HPFS), we investigated the relationship of incident type 2 DM with exposures to particulate matter (PM) <2.5 μm (PM2.5), PM <10 μm (PM10), and PM between 2.5 and 10 μm in aerodynamic diameter (PM10–2.5) in the previous 12 months and the distance to roadways.MethodsCases were reported and confirmed through biennial and supplemental questionnaires of diagnosis and treatment information. During follow-up from 1989 to 2002, questionnaires provided information on time-varying covariates and updated addresses. Addresses were geocoded and used to assign air pollution exposures from spatiotemporal statistical models.ResultsAmong participants living in metropolitan areas of the northeastern and midwestern United States, there were 3,784 incident cases of DM in the NHS, and 688 cases in the HPFS. Pooled results from random effects meta-analysis of cohort-specific models adjusted for body mass index and other known risk factors produced hazard ratios (HRs) for incident DM with interquartile range (IQR) increases in average PM during the 12 months before diagnosis of 1.03 [95% confidence interval (CI), 0.96–1.10] for PM2.5, 1.04 (95% CI, 0.99–1.09) for PM10, and 1.04 (95% CI, 0.99–1.09) for PM10–2.5. Among women, the fully adjusted HR for living < 50 m versus ≥ 200 m from a roadway was 1.14 (95% CI, 1.03–1.27).ConclusionsOverall, results did not provide strong evidence of an association between exposure to PM in the previous 12 months and incident DM; however, an association with distance to road (a proxy marker of exposure to traffic-related pollution) was shown among women.

MECHANISMS IN ENDOCRINOLOGY: Effect of long-term exposure to air pollution on type 2 diabetes mellitus risk: a systemic review and meta-analysis of cohort studies

“…One article reported two individual cohort studies, and was extracted as two individual studies (14). Thus, ten prospective cohort studies from nine articles were finally included into the meta-analysis (10,11,12,13,14,20,21,22,23).…”

“…Table 1 shows the main characteristics of those ten cohort studies included in the meta-analysis (Table 1). Those ten cohort studies involved a total of 2 371 907 participants and 21 095 incident cases of type 2 diabetes (10,11,12,13,14,20,21,22,23). Among those ten cohort studies, nine studies reported incident new cases of type 2 diabetes (10,11,13,14,20,21,22,23), while the left one reported events of deaths coded as diabetes (12).…”

“…Those ten cohort studies involved a total of 2 371 907 participants and 21 095 incident cases of type 2 diabetes (10,11,12,13,14,20,21,22,23). Among those ten cohort studies, nine studies reported incident new cases of type 2 diabetes (10,11,13,14,20,21,22,23), while the left one reported events of deaths coded as diabetes (12). There were three studies from USA (10,14), three studies from Canada (12,13,20), two studies from Germany (21,22), one from Denmark (11), and one from Switzerland (24) ( Table 1).…”

“…Among those ten cohort studies, nine studies reported incident new cases of type 2 diabetes (10,11,13,14,20,21,22,23), while the left one reported events of deaths coded as diabetes (12). There were three studies from USA (10,14), three studies from Canada (12,13,20), two studies from Germany (21,22), one from Denmark (11), and one from Switzerland (24) ( Table 1). The time of follow-up of those ten cohort studies ranged from 6 to 16 years (Table 1).…”

“…However, the effect of air pollution on type 2 diabetes risk has not been clearly described. Several studies have assessed the association between long-term exposure to air pollution and risk of type 2 diabetes, but the association remains unclear owing to the conflicting results (10,11,12,13,14). To assess the effect of long-term exposure to air pollution on type 2 diabetes risk, a meta-analysis of prospective cohort studies was performed according to the standard guideline for conducting and reporting meta-analyses of observational studies.…”