Objective: To explore the effect of extended nursing care outside hospital on self-management level and glucose control in schizophrenia (SCH) patients with diabetes mellitus (DM). Methods: Ninety patients with SCH complicated with DM who were discharged from the Minhang District of Shanghai Mental Health Center from October 2018 to November 2021 were selected. According to the hospitalized odd and even numbers, they were divided into control group and study group, each with 45 cases. The control group was given routine discharge guidance and follow-up, whereas the study group was given extended nursing intervention outside the hospital. After continued observation for 6 months, the Chinese Version Diabetes Management Self-Efficacy Scale (C-DMSES), blood glucose indexes [fasting blood glucose (FBG), 2-hour postprandial blood glucose (PBG), hemoglobin A1C (HbA1C)] and the standard rate of blood glucose control were compared between the 2 groups. Results: The scores of “diet”, “exercise” and the total score of C-DMSES in the control group were significantly higher than those before nursing (P<0.05), and the scores of various dimensions and total scores of C-DMSES in the study group were significantly higher than those before nursing (P<0.05). FBG, PBG, and HbA1C in the 2 groups were significantly lower than those before nursing at 6 months after hospital (P<0.05). FBG, PBG, and HbA1C in the study group were lower than those in the control group at 6 months after hospital, and the standard rate of blood glucose control was 57.78% higher than 35.56% in the control group (P<0.05). Conclusion: Extended nursing outside the hospital can significantly improve the self-management level of SCH patients with DM, reduce the blood glucose index level and improve the standard rate of blood glucose control.