Objective To investigate the characteristics of intestinal flora and its correlation with peripheral blood microinflammatory factors in patients with pulmonary tuberculosis complicated with diabetes mellitus(PTB-DM).Methods A total of 162 patients with PTB-DM admitted to the hospital from September 2022 to September 2024 were selected as the PTB-DM group,and another 150 healthy subjects who underwent physi-cal examinations during the same period in the hospital were selected as the control group.The clinical data of all research subjects was collected.The composition of intestinal flora of the research subjects was analyzed by using 16S rRNA gene sequencing technology.The levels of peripheral blood microinflammatory factors[inter-feron-γ(IFN-γ),interleukin-6(IL-6),and tumor necrosis factor-α(TNF-α)]in all research subjects were detected.The clinical data,composition of intestinal flora and levels of microinflammatory factors of the PTB-DM group were compared with those of the control group.Spearman correlation analysis was used to analyze the correlation between the relative abundance of intestinal flora and the levels of peripheral blood microin-flammatory factors in patients with PTB-DM.Results The relative abundances of Bacteroidales and Clostridi-ales in the PTB-DM group were significantly lower than those in the control group,while the relative abun-dances of Enterobacterales and Actinobacteriales were significantly higher than those in the control group,and the differences were statistically significant(P<0.05).The levels of IFN-γ,IL-6 and TNF-α in the PTB-DM group were significantly higher than those in the control group,and the differences were statistically signifi-cant(P<0.05).The relative abundances of Bacteroidales and Clostridiales in the PTB-DM group were nega-tively correlated with the levels of IFN-γ,IL-6 and TNF-α.The relative abundances of Enterobacterales and Actinobacteriales were positively correlated with the levels of IFN-γ,IL-6 and TNF-α(all P<0.05).Conclu-sion There is a significant imbalance of intestinal flora in patients with PTB-DM,and the levels of microin-flammatory factors IFN-γ,IL-6 and TNF-α in peripheral blood are significantly increased,and are closely re-lated to the relative abundance of specific flora.