A case risk study of lactic acidosis risk by metformin use in type 2 diabetes mellitus tuberculosis coinfection patients

Metformin (MET) has possibilities to be utilized as an adjunct of tuberculosis (TB) therapy for controlling the growth of Mycobacterium tuberculosis (M. tuberculosis). MET enhances the production of mitochondrial reactive oxygen species and facilitates phagosome–lysosome fusion; those mechanism are important in M. tuberculosis elimination. Moreover, MET-associated lactic acidosis (MALA) needs to be considered and the incidence of MALA in patients with type 2 DM–TB coinfection remains unknown. This result contributes much to our understanding about the clinical effect of MET use in type 2 DM–TB coinfection. For the purpose of understanding the MET effect as an adjuvant therapy in TB therapy and insulin simultaneous therapy, an observational clinical study was done in type 2 DM newly TB coinfection outpatients at Surabaya Paru Hospital. Patients were divided into two groups. First group was MET group, in which the patients were given MET accompanying insulin and TB treatment regimens, the golden standard therapy of DM–TB coinfection. MET therapy was given for at least 2 months. Second group was non-MET group, in which the patients were given insulin and TB treatment regimens. The lactate levels in both groups were measured after 2 months. Among 42 participants, there was no case of lactic acidosis during this study period. Data were normally distributed; thus, we continued analysis of the difference using paired T-test with 95% confidence. There was no difference in lactate levels (p = 0.396) after MET therapy compared to non-MET group. In this study involving patients with TB pulmonary diseases, there is neither evidence that MET therapy induced lactic acidosis event nor that it increased lactate blood level. Thus, we concluded that MET use in type 2 DM–TB coinfection did not induce lactic acidosis.