The risk of GDM decreased by 17.6% per 1 mmol/L increase in serum LDL-C level in a regression model that included all the study participants, with pre-pregnancy BMI, gestational age at sampling, maternal age, fasting insulin, fasting glucose, and HOMA-IR as covariates (OR = 0.824, 95% CI: 0.733–0.926, P = 0.001). The gene discussed is INS; the disease is gestational diabetes.