In addition, the T allele at VDR-rs10783219 and the C allele at CDKAL1-rs7754840 separately increased the risk of GDM subtype 1 among women with the GG genotype at MTNR1B-rs10830962 (OR = 2.99, 95%CI: 1.34–6.68; OR = 3.06, 95%CI: 1.41–6.66) (Pinteraction = 0.2611; Pinteraction = 0.0071). The gene discussed is CDKAL1; the disease is gestational diabetes.