The Impact of Organochlorine Pesticides and Lipid Biomarkers on Type 2 Diabetes Mellitus

Abstract

Type 2 diabetes mellitus (T2DM) is classified as a metabolic disorder characterized by hyperglycemia that results from defects in insulin action and/or secretion, and currently affects 8.3% of the US population according to the CDC’s 2011 National Diabetes Fact Sheet. Several contributing factors have been identified to development of this disease. Published evidence indicates type 2 diabetes mellitus (T2DM) patients display lower overall paraoxonase activity and that this may be partially due to genetic variations in the paraoxonase-1 (PON-1) gene. Some bioaccumulative organochlorine (OC) pesticides have been shown to contribute to increased T2DM prevalence. In addition, these OC compound levels have been associated with alterations in adipocyte cytokine levels as well as increased inflammatory markers. Three hundred blood samples with clinical and demographic information were obtained from two US Air Force hospitals. A total of 151 non-diabetics and 149 T2DM subjects were evaluated for PON-1 activity, PON-1 Q192R and L55M genetic polymorphisms, OC compound concentrations, inflammatory marker levels and adipokine concentrations. PON-1 activity, using diazoxon as the substrate, was decreased in the T2DM subjects. Some of the PON-1 genetic polymorphisms tested were also associated with decreased PON-1 activity. OC compound levels were increased in the T2DM subjects. The non-diabetic subjects possessing elevated DDE and trans-nonachlor were associated with increased inflammation, a common hallmark of early T2DM development. Additionally, elevated OC levels were seen in association with altered adipokine concentrations. Overall, a decrease in the antioxidant properties of PON-1 as well as factors contributing to chronic low level inflammation such as elevated OC plasma concentration appear to be significant contributors to T2DM prevalence in the population studied.