Traffic-Related Air Pollution and Incident Type 2 Diabetes: Results from the SALIA Cohort Study

Abstract

BackgroundCross-sectional and ecological studies indicate that air pollution may be a risk factor for type 2 diabetes, but prospective data are lacking.ObjectiveWe examined the association between traffic-related air pollution and incident type 2 diabetes.DesignBetween 1985 and 1994, cross-sectional surveys were performed in the highly industrialized Ruhr district (West Germany); a follow-up investigation was conducted in 2006 using data from the Study on the Influence of Air Pollution on Lung, Inflammation and Aging (SALIA) cohort.Participants1,775 nondiabetic women who were 54–55 years old at baseline participated in both baseline and follow-up investigations and had complete information available.Materials and MethodsUsing questionnaires, we assessed 16-year incidence (1990–2006) of type 2 diabetes and information about covariates. Complement factor C3c as marker for subclinical inflammation was measured at baseline. Individual exposure to traffic-related particulate matter (PM) and nitrogen dioxide was determined at different spatial scales.ResultsBetween 1990 and 2006, 87 (10.5%) new cases of diabetes were reported among the SALIA cohort members. The hazards for diabetes were increased by 15–42% per interquartile range of PM or traffic-related exposure. The associations persisted when different spatial scales were used to assess exposure and remained robust after adjusting for age, body mass index, socioeconomic status, and exposure to several non–traffic-related sources of air pollution. C3c was associated with PM pollution at baseline and was a strong independent predictor of incident diabetes. Exploratory analyses indicated that women with high C3c blood levels were more susceptible for PM-related excess risk of diabetes than were women with low C3c levels.ConclusionsTraffic-related air pollution is associated with incident type 2 diabetes among elderly women. Subclinical inflammation may be a mechanism linking air pollution with type 2 diabetes.Relevance to clinical practiceOur study identifies traffic-related air pollution as a novel and potentially modifiable risk factor of type 2 diabetes.

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).…”

“…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).…”

“…All studies reported adjusted estimates, but the adjusted factors were various and different from each other ( Table 1). There were five cohort studies on PM2.5 (10,12,13,14), six cohort studies on NO 2 (10,11,20,21,22,23), and four cohort studies on PM10 (14,21,23) respectively (Table 1). According to the quality criteria, there were seven cohort studies with A level quality (10,11,13,14,21,23), and the other three studies with B level quality (12,20,22) (Table 1).…”