Objective To analyze the effect of metformin combined with pioglitazone in the treatment of diabetes melli-tus.Methods A total of 100 patients with diabetes admitted to the Internal medicine Department of Zherong County Hospital of Traditional Chinese Medicine from August 2022 to August 2023 were selected as the study objects by sam-pling method.The patients were divided into control group and observation group by random odd-even number method,with 50 cases in each group.The control group was given metformin treatment,and the observation group was com-bined with pioglitazone.The clinical effects,blood glucose control,lipid metabolism indexes and the incidence of ad-verse reactions were compared between the two groups.Results The total clinical effective rate of the observation group was 96.00%,higher than that of the control group(84.00%),and the difference was statistically significant(P<0.05).After 4 weeks of treatment,the blood glucose index levels of the observation group were lower than those of the control group,and the differences were statistically significant(all P<0.05).The results of 4 terms of serum lipids in the obser-vation group were better than those in the control group,and the differences were statistically significant(all P<0.05).There was no significant difference in the incidence of adverse reactions between the two groups(P>0.05).Conclusion Metformin combined with pioglitazone is effective in the treatment of diabetes mellitus and more significant in improv-ing glucose and lipid metabolism,while the combination of drugs will not increase the adverse drug reactions.