Objective To analyze the clinical effect of metformin combined with insulin in the treatment of pediatric diabetes mellitus.Methods 78 cases of pediatric diabetes mellitus admitted to the Yuncheng County People's Hospi-tal from March 2022 to March 2023 were selected as the research objects and divided into two groups according to random number table method,with 39 cases in each group.The monotherapy group was treated with insulin,and the combination group was treated with metformin combined with insulin.The treatment efficiency,blood glucose index and the incidence of adverse reactions were compared between the two groups.Results The total effective rate of com-bination group was higher than that of monotherapy group,the difference was statistically significant(P<0.05).After treatment,the blood glucose index of combination group was lower than that of monotherapy group,and the difference was statistically significant(P<0.05).The total incidence of adverse reactions in combination group was lower than that in monotherapy group,and the difference was statistically significant(P<0.05).Conclusion Metformin combined with insulin is effective and safe in the treatment of pediatric diabetes.