Abstract: OBJECTIVE To observe and analyze the effects of different antimicrobial therapy regimens on serum markers and curative effect of elderly patients with diabetes mellitus complicated with pulmonary infections. METHODS A total of 58 patients with senile diabetes mellitus complicated with pulmonary infections who were treated with ceftazidime combined with ambroxol in our hospital from Apr. 2014 to Feb. 2016 were selected as observation group, and 60 patients treated with cefotaxime sodium combined with ambroxol were set as control group. The changes of serum markers of the two groups before and after treatment were compared, while the efficacy and adverse drug reactions 10 days after treatment were compared. RESULTS After treatment, the levels of serum ET, CRP and WBC and CGRP had significant differences with those before treatment (P＜0.05). CD₄⁺/CD₈⁺ were significantly improved in observation group and CD₄⁺/CD₈⁺ in control group had no significant improvement. The levels of ET, CRP, WBC, CGRP, and CD₄⁺/CD₈⁺ in observation group after treatment were (41.63 ± 5.17) ng / L, (51.39 ± 8.67) mg/L, (8.37 ± 4.25) ×10⁹ / L, (67.53 ± 5.43) ng/L, and (1.56±0.23), which were significantly higher than (58.37±6.03)ng/L, (87.69±8.75)mg/L, (11.68±4.37)×10⁹/L, (50.34±4.56)ng/L, and (1.04±0.15) in control group (P<0.05). The total effective rate in observation group was 82.76%, which was significantly higher than 66.67% in control group (P<0.05). The incidence of complications in observation group was 8.62%, which was significantly lower than 16.67% in control group (P<0.05). CONCLUSION Ceftazidime combined with ambroxol as a broad-spectrum bactericidal regimen not only significantly inhibits the expression of inflammatory cytokines, but also has a beneficial regulatory effect on immune function.