Objective To analyze and compare the effects of insulin therapy on blood glucose control and pregnancy outcomes in pregnant women with diabetes at different stages. Methods: 80 patients with gestational diabetes admitted in our hospital from January 2021 to June 2022 were selected and divided into two groups according to the random number table. On the basis of routine intervention, the control group and the study group were treated with insulin after 32 weeks of gestation and at ≤ 32 weeks of gestation (that is, when the disease was diagnosed). The treatment effects of the two groups were compared until the delivery of pregnant women. Results: Compared with the control group, the levels of FPG, HbAlc and 2hPG in the study group were significantly lower after treatment (P<0.05). After treatment, HOMA-IR, body mass index and total effective rate were compared between the two groups (P<0.05). The incidence of adverse outcomes of pregnant women and perinatal infants in the study group was lower than that in the control group (P<0.05). Conclusion: Insulin treatment for pregnant women at gestational age ≤ 32 weeks can achieve more ideal effect than that after 32 weeks. It can better control the blood sugar of patients, optimize the outcome of pregnant women and perinatal infants, and ensure the safety of mothers and infants.