Metformin reduces risk of active tuberculosis in T2DM patients
Metformin is the only medication among all types of antidiabetic therapy (ADT) and insulin therapies that lowers the risk of active tuberculosis (TB) in the type 2 diabetes mellitus (T2DM) population, a recent study has shown.
However, the beneficial effect of using metformin attenuates in the elderly population and is not seen in patients with metabolic disorders.
The rate of incident TB was significantly higher among patients with T2DM than control participants (adjusted hazard ratio, 2.01; 95 percent CI, 1.80–2.25). Metformin use independently predicted a reduced risk of active TB (adjusted relative risk [aRR], 0.24; 0.18–0.32) after adjusting for comorbidities, diabetes complications, ADT type and statin use.
The association between metformin use and active TB risk persisted in most subgroup analyses, except for patients with metabolic disorders (aRR, 0.46; 0.11–1.87). The protective effect of metformin was dose-dependent but gradually weakened in the elderly population.
In this nationwide population-based cohort study that assessed the risk of active TB among persons with T2DM who were treated with various ADT and insulin therapies, the investigators used the Taiwan Longitudinal Health Insurance Database to identify T2DM patients (n=49,028). Of these, 44,002 were metformin users and 5,026 were nonusers.
There were 5,026 propensity score-matched pairs of metformin users and nonusers with T2DM who were assessed from 1998 to 2010. Cox proportional hazard models were used to analyse the data.
“Metformin is an oral ADT to manage T2DM and has been reported to have potential anti‐TB effects,” the investigator said.