It has been suggested that there is an association between environmental, low-level arsenic exposure and the risk of diabetes mellitus (DM), but little research has been conducted. Here, the glucose tolerance status and urinary creatinine adjusted total arsenic concentrations were analyzed in 3,602 subjects ≥ 20 yr of age who were registered for the Korea National Health and Nutrition Examination Survey, 2008-2009. Various demographic parameters were associated with urinary arsenic concentrations. After adjusting for these variables, urinary arsenic concentrations in subjects with DM were significantly higher than those in subjects with normal glucose tolerance and those with impaired fasting glucose (P < 0.001). Compared with the lowest quartile ( < 70.7 µg/g creatinine), the odds ratios and 95% confidence intervals for DM were 1.11 (0.73-1.68), 1.42 (0.94-2.13), and 1.56 (1.03-2.36) for urinary arsenic concentrations of 70.7 to < 117.7, 117.7 to < 193.4, and ≥ 193.4 µg/g creatinine, respectively, following multivariate adjustment. Furthermore, the urinary total arsenic concentration was inversely associated with the insulin secretion index, HOMA2 %B (β = -0.033, P = 0.032). These findings suggest that arsenic exposure, possibly involving beta cell dysfunction, is associated with an increased risk of DM in the Korean population.