In this study, we selected 9 single nucleotide polymorphisms (SNPs) within 4 representative genes (VDR, GC, CYP2R1, and CYP24A1) encoding the core proteins involved in vitamin D production, degradation, and ligand-dependent signaling, in order to evaluate a potential relationship between these genetic variants and GDM. The gene discussed is GC; the disease is gestational diabetes.