Patients with type 2 diabetes (T2D) treated with sulfonylureas may be at a higher risk of contracting tuberculosis (TB) compared with patients treated with metformin, according to a study published in CHEST.

The researchers identified 40,179 individuals with T2D from the Taiwan National Heath Insurance Research Database and conducted a retrospective, nationwide population-based cohort study placing individuals studied in 2 groups: metformin-majors (receiving metformin ≥60 cumulative defined daily dose [cDDD] and sulfonylureas <15 cDDD) and sulfonylurea-majors (sulfonylureas ≥60 cDDD and metformin <15 cDDD). Individuals in both groups were matched 1:1 by propensity score and retrospectively followed for at least 2 years.

Study results demonstrated a lower TB risk in metformin majors compared with sulfonylurea majors both before and after being matched by propensity score (adjusted hazard ratio [aHR], 0.477 [95% CI, 0.268-0.850] and aHR, 0.337 [95% CI, 0.169-0.673]; matched n=3161 pairs). In addition, the reference group had a dose-dependent TB risk compared with those treated with metformin (60-219 cDDD; aHR, 0.860 [95% CI, 0.637-1.161]; 220-479 cDDD; aHR, 0.706 [95% CI, 0.485-1.028]; ≥480 cDDD; aHR, 0.319 [95% CI, 0.118-0.863]).

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The researchers concluded that T2D treatment in the first 2 years with metformin was associated with a decreased risk for TB compared with treatment with sulfonylureas. In addition, the dosage of metformin, not sulfonylureas, was found to be independently associated with a decreased risk for TB. Therefore, clinicians should first consider the use of metformin for the initial treatment of T2D in high-risk individuals unless contraindicated.

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Pan SW, Yen YF, Kou YR, et al. The risk of tuberculosis disease in type 2 diabetes patients initiating metformin versus sulfonylureas [published online December 16, 2017]. CHEST. doi:10.1016/j.chest.2017.11.040