The role of metformin (MET) on treatment effect of diabetic tuberculosis (TB) patients has not been studied in China. Thus, we conducted a retrospective study to investigate whether MET exhibited more efficacy in combination with anti-TB regimens for diabetic TB patients. All patients recruited came from five tuberculosis control and prevention institutes from July 2009 to July 2016 and completed 3 years of follow-up. We used chi-square test or Fisher's exact test to evaluate the demographic characteristics and the frequency of clinical outcome between MET and non-MET group. A total of 58 TB patients with diabetes mellitus (DM), of these 27.6% (16/58) patients in the MET group and 72.4% (42/58) patients in the non-MET group, there was no significant difference in blood glucose level between MET and non-MET group (P = 0.494), in addition, there was a higher proportion of treatment success (93.8 vs. 71.4%) and culture conversions by the end of 2 months (87.5 vs. 71.4%) among MET group; the relapse rates of patients in MET and non-MET group were 6.3% (1/16) and 35.7% (15/42) through a 3-year follow-up (P = 0.045). Our data revealed that the use of MET as a combination drug with existing regimen improved the success rate of anti-TB treatment and reduced the relapse rate in TB patients with DM.

Highlights Serum cytokine levels may correlate with tuberculosis patient disease status. Serum TNF-α level may be a useful biomarker for predicting bacillar burden. Serum TNF-α and IFN-γ levels may reliably monitor anti-TB treatment progress. Serum IL-4 level had no value while serum IL-2R level value awaits further study. Cytokine biomarkers are useful biomarkers in clinical TB patient care settings.