Gestational diabetes mellitus (GDM) is a common complication of pregnancy, posing obstetrical and metabolic risks. While emerging evidence suggests an association between specific metal exposure and GDM, the crucial metabolic changes between serum metal exposure and GDM risk have yet to be fully clarified. Here we employed a combination of bibliometric and epidemiological methodologies to investigate the relationship between metal exposure and GDM and potential mediation role of metabolites in Chinese pregnant women. Our findings revealed an increasing research interest in the association of serum metal levels with GDM. Epidemiologically, metals such as iron (Fe) and molybdenum (Mo) were found to be negatively associated with GDM based on single-metal models with ORs being 0.325 (95 % CI: 0.138, 0.768) and 0.030 (95 % CI: 0.002, 0.439), respectively. A joint negative effect from metal co-exposure on GDM was shown, with Fe and Mo identified as the key metals. 7β-hydroxycholesterol mediated 9.9 % of the association between Fe and GDM risk, while melatonin mediated 7.8 % of the association between Mo and GDM risk. Our study provides new perspectives for understanding the beneficial effect of essential metals on GDM and lays a solid foundation for further validation through multicenter investigations and for exploration of mechanisms through in vivo studies.

Thyroid homeostasis is essential for human health, and arsenic (As) and mercury (Hg) have drawn considerable attention due to their bioaccumulation and potential health risks. However, evidence on their thyroid-disrupting effects remains inconsistent and largely derived from cross-sectional studies, hindering causal inference and risk integration. Here, a meta-analysis was first conducted, which confirmed that both As (Cohen’s d = 0.45, 95% CI: 0.10, 0.81) and Hg (Cohen’s d = 0.40, 95% CI: 0.16, 0.65) exposure were associated with an increased risk of thyroid dysfunction. To further clarify temporality, we analyzed prospective cohort data from 800 adult women in Jiangsu, China. Results showed that As exposure was linearly and positively associated with free thyroxine (FT4) (β = 0.19, 95% CI: 0.01, 0.37), while Hg showed an inverted U-shaped dose–response relationship with FT4 levels. Based on the above epidemiological evidence, we further integrated in vivo and in vitro evidence from published related literature, applied the Targeted Risk Assessment for Environmental Chemicals (TRAEC, ver.1.1) strategy, and obtained final scores of 7.79 for As and 7.09 for Hg (out of 10), indicating a moderate level of thyroid-related health risk. Collectively, these findings suggest that As and Hg exposure may disturb thyroid function, supporting the need for targeted mitigation and further mechanistic research.