Objective. To explore the clinical effect and impact of exercise-diet therapy combined with Insulin Aspart Injection on gestational diabetes mellitus (GDM). Methods. The objects of study were patients with pregestational diabetes mellitus (PGDM) and 62 patients with GDM who were diagnosed by oral glucose tolerance test (OGTT) and insulin release test from February 2017 to February 2019. According to the severity of the disease, enrolled patients were informed to have appropriate exercise and diet control or Insulin Aspart Injection on this basis until the completion of delivery. By using 50 pregnant women with normal glucose as the control, the fasting plasma glucose (FPG), 1-hour postprandial glucose (1hPG), 2-hour postprandial glucose (2hPG), nocturnal glucose, and glycosylated hemoglobin (HbA1c) levels were compared between the PGDM group and the GDM group before and after treatment; besides, further comparison was made in terms of glucose compliance rate, islet B-cell secretory function, and insulin resistance after treatment. The pregnant women were examined by B-ultrasound at 24 and 26 weeks of gestation to check if the fetus had abnormalities in the central nervous system and the heart. Further B-ultrasound examination was performed at 32 and 37 weeks of gestation to check the problems such as polyhydramnios and stillbirth. In addition, a comparative analysis was carried out in terms of the adverse pregnancy outcomes and complications, associated with the comparison of the results after treatment with control group. Results. After treatment, the levels of FPG, 1hPG, 2hPG, nocturnal glucose, and HbA1c were decreased in the PGDM group and GDM group than those before treatment, especially in the GDM group, with significant difference still when compared with the control group (P < 0.05). Statistical analysis revealed that the blood glucose compliance rate in the GDM group was higher than that in the PGDM group, showing a better therapeutic effect. Fasting insulin (FINS) and homeostasis model assessment index for insulin resistance (HOMA-IR) in the GDM group were significantly higher than those in control group, but lower than those in the PGDM group (P < 0.01), while the level of HOMA-β was lower in the GDM group than that in the control group and higher than that in PGDM (P < 0.01). Further ultrasound examination revealed the presence of fetal cardiac abnormality, polyhydramnios, stillbirth, and problems, showing a higher incidence in the PGDM group but almost nonexistence in the control group. In addition, the incidence of hypertension, macrosomia, premature rupture of membranes, postpartum hemorrhage, and infection were obviously higher in the PGDM group than those in the GDM group and control group (P < 0.05). Conclusion. Exercise-diet therapy combined with Insulin Aspart Injection can effectively control the blood glucose level of pregnant patients with GDM, improve the pregnancy outcome to a certain extent, and ensure the health of pregnant women and fetus, which is worthy of clinical application. [ABSTRACT FROM AUTHOR]