We retrieved studies from the PubMed, Ovid, and Wiley from the inception of the databases to June 2021, with the search terms “gestational diabetes mellitus” and “preeclampsia.” We cross-referenced these terms with “obesity,” “body mass index,” “gestational weight gain,” “early onset,” “blood glucose,” “polycystic ovary syndrome,” “twin pregnancy,” “management,” “mechanism,” “predictive markers,” “risk factors,” “insulin,” “metformin,” “Glibenclamide.” We carefully screened all the articles, and focused on articles covering multivariate analysis to judge the independent correlation. The gene discussed is INS; the disease is gestational diabetes.