Long-term effects of arsenic on glucose-insulin homeostasis: A gene-environment interaction study

Abstract Background Arsenic exposure and genetic factors are associated with an increased risk of type 2 diabetes, yet study of environment-gene interaction on glucose-insulin homeostasis remains scarce. We aimed to investigate the associations and interactions of urinary total arsenic (UTAs) and genetic susceptibility with glucose-insulin homeostasis through a longitudinal epidemiological study. Methods A total of 6136 observations (3063 participants) from the baseline, 3-year follow-up, and 6-year follow-up of the Wuhan-Zhuhai cohort were included in this study. In each study period, we repeatedly measured UTAs, fasting plasma glucose (FPG), fasting plasma insulin (FPI), and homeostasis model-assessed insulin resistance (HOMA-IR) and β-cell function (HOMA-β). Polygenic risk scores (PRSs) specific for all traits were constructed by corresponding genome-wide association summary statistics. Linear mixed models were used to assess associations and interactions of UTAs and PRSs with four indicators of glucose-insulin homeostasis. Results After adjustment for all covariates, the βs (95% CIs) for the annual growth rates of FPG, FPI, and HOMA-IR were 0.020 (0.008, 0.032), 0.007 (0.002, 0.013), and 0.011 (0.004, 0.017), respectively, associated with each ln-unit increase in UTAs. Compared to subjects with the first-quartile PRS and low UTAs, participants with the fourth-quartile PRS and high UTAs had a 0.029 (0.012, 0.047) or 0.032 (0.012, 0.051) ln-unit increase in the annual growth rate of FPI or HOMA-IR, respectively. UTAs and PRS had significant interactions on the longitudinal progressive increases of FPI and HOMA-IR (P interaction < 0.05). Conclusions Arsenic exposure and genetic variants are significantly synergistic risk factors for dysregulation and progressive deterioration of glucose-insulin homeostasis. Our findings emphasize the importance of reducing arsenic exposure to maintain normal glucose-insulin metabolism, especially for those at higher genetic risk. Key messages • Arsenic exposure was associated with annual increased rates of FPG, FPI, and HOMA-IR. • Arsenic exposure and trait-specific PRSs are synergistic risk factors for glucose-insulin homeostasis impairment.