Objective:To investigate the effects of urinary nickel exposure on insulin resistance, islet function and diabetes risk in adults aged 18 years and above in China.Methods:Based on the China National Human Biomonitoring from 2017 to 2018, a total of 500 diabetes patients were randomly selected as the case group, and the matched euglycemic control were selected by 1∶1 matching ratio. The urinary and venous blood samples of the subjects were collected, and the urinary nickel levels and serum glucose metabolism indexes such as fasting blood glucose and fasting insulin were detected, and the insulin resistance index (HOMA-IR), β cell function index (HOMA-β), and adjusted HOMA-β were calculated by using homeostasis model assessment. A multivariate logistic regression model was used to analyze the association between urinary nickel level and diabetes risk. Multiple linear regression models were used to evaluate the association of urinary nickel level with HOMA-IR, HOMA-β and adjusted HOMA-β.Results:The sex ratio of controls and cases was 1∶1. The multivariate logistic regression model showed that after adjusting for factors such as education level, smoking status, alcohol consumption, rice and meat intakes, family history of diabetes, BMI, total cholesterol level, hypertension, and urinary creatinine, compared with T1 group, the ORs of diabetes risk in the T2 and T3 groups were 1.36 (95% CI: 0.98-1.89) and 1.60 (95% CI: 1.14-2.24), respectively. The multiple linear regression model showed a positive association between urinary nickel levels and the elevated HOMA-IR, the β value of HOMA-IR in the T3 group was 0.12 (95% CI: 0.01-0.25) compared with the T1 group and each one-unit increase in the log-transformed urinary nickel level (2.71 μg/L) was associated with a 0.06 elevation in HOMA-IR (95% CI: 0.02-0.10). Meanwhile, the urinary nickel levels were negative associated with the adjusted HOMA-β, the β value of adjusted HOMA-β in the T3 group were -0.26 compared with the T1 group (95% CI: -0.41- -0.11), and each one-unit increase in the log-transformed urinary nickel level (2.71 μg/L) was associated with a -0.09 decrease in adjusted HOMA-β(95% CI: -0.14- -0.04). Conclusion:Higher urinary nickel level is positively correlated with elevated insulin resistance and diabetes risk while negatively correlated with the function of pancreatic islet β cells in adults in China.