Long-term arsenic exposure and incidence of non-insulin-dependent diabetesmellitus: A cohort study in arseniasis-hyperendemic villages in Taiwan

Diabetes prevalence in arseniasis-hyperendemic villages in Taiwan has been reported to be significantly higher than in the general population. The aim of this cohort study was to further evaluate the association between inges ted inorganic arsenic and the incidence of non-insulin-dependent diabetes m ellitus in these villages. A total of 446 nondiabetic residents in these vi llages were followed biannually by oral glucose tolerance test. Diabetes is defined as a fasting plasma glucose level greater than or equal to 7.8 mmo l/L andlor a 2-hr post-load glucose level greater than or equal to 11.1 mmo l/L. During the follow-up period of 1499.5 person-years, 41 cases developed diabetes, showing an overall incidence of 27.4/1,000 person-years. The inc idence of diabetes correlated with age, body mass index, and cumulative ars enic exposure. The multivariate-adjusted relative risks were 1.6, 2.3, and 2.1 for age greater than or equal to 55 versus < 55 years, a body mass inde x greater than or equal to 25 versus < 25 kg/m(2), and a cumulative arsenic exposure greater than or equal to 17 versus < 17 mg/L-years, respectively. The incidence density ratios (95% confidence intervals) between the hypere ndemic villages and the two nonendemic control townships were 3.6 (3.5-3.6) , 2.3 (1.1-4.9), 4.3 (2.4-7.7), and 5.5 (2.2-13.5), respectively, for the a ge groups of 35-44, 45-54, 55-64, and 65-74 years. The findings are consist ent with our previous cross-sectional observation that ingested inorganic a rsenic is diabetogenic in human beings.