The association between mixed exposure to multiple metals and the risk of abnormally elevated blood glucose among aluminum factory workers.

This study aims to analyze the connection between mixed metal exposure and abnormal blood glucose (defined as fasting plasma glucose ≥6.1 mmol/L, according to the World Health Organization diagnostic criteria) among aluminum plant workers. A total of 384 male workers from a large aluminum plant in Shanxi Province were surveyed between July and August 2024. Fasting glucose and eight plasma metals were measured. Logistic regression, Restricted cubic spline (RCS) analyses, least absolute shrinkage and selection operator (LASSO) regression, Weighted quantile sum (WQS) regression, and Bayesian kernel machine regression (BKMR) were used to examine single-metal and mixture effects. Following adjustment for potential confounders, the highest quartile (Q4) of plasma aluminum, selenium, and copper was associated with higher odds of abnormal blood glucose, with adjusted ORs of 2.93 (95% CI: 1.16-7.40), 2.30 (95% CI: 1.05-5.05), and 2.71 (95% CI: 1.17-6.27), respectively, compared with the lowest quartile (Q1). RCS analyses further indicated positive, approximately linear dose-response relationships across the observed concentration ranges for these three metals. LASSO regression identified aluminum, selenium, and copper as key metals. WQS regression revealed an overall positive association between mixed metal exposure and abnormal blood glucose, with aluminum and selenium contributing the most, with weights of 0.434 and 0.375, respectively. BKMR analyses suggested positive exposure-response trends for individual metals, with no strong evidence of interactions. These findings suggest that higher plasma aluminum, selenium, and copper are associated with a higher likelihood of abnormal blood glucose among aluminum plant workers. Targeted strengthening of occupational health protection is necessary.