The increasing prevalence of drug-resistant strains of Mycobacterium tuberculosis—the bacterium that causes tuberculosis (TB)—has led to a paradigm shift in the search for new drugs. Rather than targeting the bacterium itself, researchers are trying to augment host defenses. Now, Singh et al. report that the FDA-approved drug metformin, currently used to treat type 2 diabetes, can improve the immune response to M. tuberculosis infection. Metformin inhibited the growth of M. tuberculosis by enhancing specific immune responses in vitro and in infected mice. Furthermore, in human diabetic patients with TB, metformin treatment decreased TB severity.
Sci. Transl. Med. 6, 263ra159 (2014).