LEP and gestational diabetes: A cross-sectional study by Zhang et al. 2021 [56] found that low serum Nrg4 levels were negatively associated with FPG, HOMA-IR and leptin as well as pro-inflammatory cytokines interleukin 6 (IL-6), tumour necrosis factor-alpha (TNF-α), and monocyte chemoattractant protein-1 (MCP-1) in GDM.