Relationship between Blood Concentrations of Persistent Organic Pollutants and Regional Difference in Risk of Type 2 Diabetes in Germany

Abstract

Introduction: Although most persistent organic pollutants (POPs) are now banned in many countries, they can still be detected in the food chain and can also accumulate in adipose tissue. POPs mainly include polychlorinated biphenyls (PCBs), organochlorine pesticides, and hexachlorobenzene (HCB). We recently found substantial regional differences in the incidence of (pre-)diabetes in Germany with higher estimates in the Northeast than in the West and South, which were not fully explained by traditional risk factors. We hypothesize that differences in current diabetes risk between regions of the former German Democratic Republic and Federal Republic of Germany may partly be a result of differing exposure to POPs. Methods: We investigated the association of several POPs and the risk of type 2 diabetes (T2D) in two nested case-control studies of the cohorts CARLA in Halle (East Germany) and KORA in Augsburg (South Germany). Seventy-seven and 60 cases with incident T2D and 154 and 120 age- and sex-matched nondiabetic controls from CARLA and KORA, respectively, were included. Blood concentrations of PCBs 138, 153, 180, HCB, β-HCH and p,p’-DDE were measured using gas chromatographic high-resolution mass spectrometry. POP concentrations were categorized in tertiles among controls. Odds ratios (OR) with 95%-confidence intervals for incident T2D were estimated using conditional logistic regression adjusting for body mass index and total cholesterol. Results: In CARLA, all PCBs showed higher risks in the third tertiles compared to the lowest tertiles with the strongest association present in PCB 138 (OR: 2.74 [1.16-6.46]). Of all POPs evaluated, β-HCH showed the strongest association with incident T2D (OR: 2.78 [1.02-7.60]). Analyses for KORA are ongoing. Conclusions: POPs seem to increase the risk for T2D in CARLA, probably through endocrine disruption. Further analyses will investigate to which extent POPs might explain regional differences in T2D incidence in Germany.