Lee MC, et al. - Researchers examined the protective effect of metformin against active tuberculosis (TB) among TB close contacts. From the National Health Insurance Research Database of Taiwan, they analyzed 5,846 TB close contacts who were metformin users, metformin non-users, and healthy contacts. The incidence of active TB was 755 (600–938), 1,117 (927–1335), and 526 (393–689) cases per 100,000 person-years in each respective group. The analysis revealed a lower risk of developing active TB among TB close contacts with diabetes mellitus in correlation to metformin use; this was particularly noted for insulin users. Findings suggested that, in the event of no contraindications, metformin may be an alternative choice for primary prevention against active TB.