Metformin use & asthma outcomes in patients with concurrent diabetes & bronchial asthma: A systematic review & meta-analysis

Document Type

Article

Publication Title

Indian Journal of Medical Research

Abstract

Background & objectives Limited data exist on the effects of metformin on asthma outcomes in patients having type 2 diabetes (T2D) along with asthma. This meta-analysis seeks to determine whether metformin influences asthma outcomes in these patients. Methods Studies involving adults with T2D and asthma, using metformin in the intervention group and other glucose-lowering drugs in the control group, were systematically searched through databases. The primary outcome was the adjusted risk of asthma exacerbations in metformin users (MU) vs. non-metformin users (non-MU). Other outcomes included asthma-related emergency room visits, hospitalisations, and the need for rescue steroids. Meta-analysis was conducted using RevMan with random-effects models. Outcomes were reported as hazard ratios (HRs) with 95 per cent confidence intervals (95% CI). Results Six retrospective cohort studies with moderate overall risk of bias, involving 317,905 patients, were included. The risk of asthma exacerbation was comparable in MU and non-MU (HR 0.95, 95% CI: 0.86, 1.04, P=0.27). The risk of asthma-related emergency room visits appeared lower in MU than in non-MU, though the difference did not gain statistical significance (HR 0.63, 95% CI: 0.39, 1.01, P=0.06). The two groups also had statistically identical risks of asthma-related hospitalisations (HR 0.76, 95% CI: 0.54, 1.07, P=0.12) and use of rescue steroids (HR 0.95, 95% CI: 0.87, 1.03, P=0.24). However, after excluding a study from Taiwan (n=115486), a significantly lower risk of asthma exacerbation (HR 0.89, 95% CI: 0.83-0.97, P=0.005) and asthma-related hospitalisations (HR 0.68, 95% CI: 0.49-0.93, P=0.02) was observed in MU. Interpretation & conclusions Metformin therapy for T2D does not influence asthma outcomes; however, certain outcomes appear to improve when a Taiwanese study is excluded. Such results must be considered cautiously, as the included studies are observational and have a moderate risk of bias. Randomised controlled trials with diverse global representation are essential for clarifying the relationship between metformin use and asthma outcomes.

First Page

187

Last Page

196

DOI

10.25259/IJMR_431_2025

Publication Date

8-1-2025

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