Relationship between urinary bisphenol A levels and prediabetes among subjects free of diabetes

Bisphenol A (BPA) is a high volume production chemical used in the manufacture of polycarbonate plastics and epoxy resins. Recent experimental studies have suggested that BPA affects glucose metabolism through diverse mechanisms including insulin resistance, pancreatic beta-cell dysfunction, adipogenesis, inflammation and oxidative stress. Prediabetes is a stage earlier in the hyperglycemia continuum associated with increased future risk of developing diabetes. Therefore, we examined the association between BPA exposure and prediabetes among subjects free of diabetes. We examined the association between urinary BPA levels and prediabetes in 3,516 subjects from the National Health and Nutritional Examination Survey 2003-2008. Urinary BPA levels were examined in tertiles. Prediabetes was defined as fasting glucose concentration 100-125 mg/dL or 2-h glucose concentration of 140-199 mg/dL or an A1C value of 5.7-6.4 %. Overall, we observed a positive association between higher levels of urinary BPA and prediabetes, independent of potential confounders including body mass index, alcohol intake, blood pressure and serum cholesterol levels. Compared to tertile 1 (referent), the multivariate-adjusted odds ratio (95 % confidence interval) of prediabetes associated with tertile 3 of BPA was 1.34 (1.03-1.73), p-trend = 0.02. In subgroup analysis, this association was stronger among women and obese subjects. Higher urinary BPA levels are found to be associated with prediabetes independent of traditional diabetes risk factors. Future prospective studies are needed to confirm or disprove this finding.