Objective: The aim of the present study was to explore the impact of the one-day clinic diabetes mellitus (DM) management model on perinatal outcomes in patients with gestational diabetes mellitus (GDM). Methods: A total of 995 patients who underwent prenatal checkups at our hospital and were diagnosed with GDM by oral glucose tolerance test (OGTT) screening at 24-28 weeks of gestational age were enrolled between December 2018 and August 2020. The patients were randomly divided into a study group (541 cases) and a control group (454 cases). One-day clinic intervention for DM was conducted in the study group, while individualized dietary interventions and exercise instruction were given in the control group. The perinatal outcomes of patients were compared between the two groups. Results: In the study group, maternal weight gain, fasting blood glucose before delivery, the incidence of abnormality in postpartum OGTT, and abnormality of pancreatic islet function were lower than in the control group, and the differences were statistically significant (P < 0.05). The percentage of patients with insulin treatment in the study group was higher than in the control group, and the difference was statistically significant (P < 0.05). The incidence of premature rupture of membranes, macrosomia, and neonatal jaundice was lower in the study group than in the control group, and the differences were statistically significant (P < 0.05). Conclusion: The one-day clinic DM management model can effectively control weight gain and blood glucose levels during pregnancy in patients with GDM, resulting in a higher recovery rate of blood glucose and islet function after delivery and a lower incidence of premature rupture of membranes, macrosomia, and neonatal jaundice. The one-day clinic DM management model could therefore have profound implications for reducing and delaying the onset of postpartum type 2 diabetes in patients with GDM.