OBJECTIVES: AMPK-activating antidiabetic drug metformin inhibits the intracellular growth of Mycobacterium tuberculosis (Mtb), restricts disease immunopathology, and enhances Mtb-specific host immunity, reduces inflammation and promotes disease resolution. This study was based on the hypothesis that AMPK-activating metformin boost the host immunity and thereby protect against TB infections in diabetics. Objective of the study was to determine the protective effect of metformin against TB in diabetics.  METHODS: A case-control study was conducted using hospital databases of patients admitted with newly diagnosed diabetics (without any previous history of TB infection) in Medicine department of a tertiary care hospital in South India during 1st January 2011 to 31st December 2015. The newly diabetics diagnosed with TB were selected as Study Group (SG=152) and without TB were as Control Group (CG=299). Exposure statuses of metformin in both groups were analyzed. RESULTS: Mean age (±SD) of study population was found to be 54.67 ±