A Prospective Analysis in the Nurses' Health Study and Meta-analysis
BACKGROUND: Prospective data regarding persistent organic pollutants (POPs) and risk of type 2 diabetes (T2D) are limited, and the results for individual POPs are not entirely consistent across studies. OBJECTIVES: To prospectively examine plasma POP concentrations in relation to incident T2D and summarize existing evidence in a meta-analysis. METHODS: Plasma polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethylene (DDE), and hexachlorobenzene (HCB) concentrations were measured in 1,095 women who were free of diabetes at blood draw in 1989-1990 and participated in two case-control studies in the Nurses' Health Study. We identified 48 incident T2D cases through June 30, 2008. We conducted a literature search in MEDLINE and EMBASE through December 2011 to identify prospective studies on POPs in relation to diabetes. We used a fixed-effects model to summarize results. RESULTS: After multivariable adjustment, plasma HCB concentration was positively associated with incident T2D [pooled odds ratio (OR) 3.59 (95% CI: 1.49, 8.64, P for trend = 0.003) comparing extreme tertiles]. Other POPs were not significantly associated with diabetes. After pooling our results with those of 6 published prospective studies that included 842 diabetes cases in total, HCB and total PCBs both were associated with diabetes: the pooled ORs were 2.00 (95% CI: 1.13, 3.53; I2 = 21.4%, Pheterogeneity = 0.28) and 1.70 (95% CI: 1.28, 2.27; I2 = 16.3%, Pheterogeneity = 0.30) for HCB and total PCBs, respectively. CONCLUSIONS: These findings support an association between POP exposure and the risk of type 2 diabetes.
Environmental Health Perspectives, 2013, Vol 121, Issue 2, p. 153-61