Metformin, a common diabetes medication, may lower the frequency of asthma attacks in people with type 2 diabetes, according to a study published in JAMA Internal Medicine. The study also suggests that combining metformin with glucagon-like peptide-1 receptor agonists (GLP-1 RAs) may provide additional benefits.

The research, led by Bohee Lee, Ph.D., from Imperial College London, analyzed data from the U.K. Clinical Practice Research Datalink Aurum, covering the years 2004 to 2020. The study included individuals newly prescribed metformin for type 2 diabetes and evaluated the association of metformin and other antidiabetic medications with asthma exacerbations.

Among 4,278 patients in the self-controlled case series (SCCS) and 8,424 patients in the inverse probability of treatment weighting (IPTW) cohort, metformin use was associated with a significant reduction in asthma attacks. The incidence rate ratio in the SCCS analysis was 0.68, while the hazard ratio in the IPTW cohort was 0.76, indicating a consistent finding across methodologies.

Importantly, the association between metformin and reduced asthma exacerbations was not influenced by hemoglobin A1c levels, body mass index, blood eosinophil counts, or asthma severity, suggesting mechanisms unrelated to glycemic control or weight loss. GLP-1 RAs, used as an add-on therapy, further reduced asthma attacks, with an incidence rate ratio of 0.60 in the SCCS analysis.

"The results of this cohort study suggest that metformin was associated with a lower rate of asthma attacks, with further reductions observed when combined with GLP-1 RA therapy," the authors wrote. "These effects appeared to work through mechanisms independent of glycemic control and weight loss and were consistent across different asthma phenotypes."

This research highlights the potential for repurposing antidiabetic medications like metformin and GLP-1 RAs to manage asthma, though further studies are needed to confirm these findings and uncover the underlying mechanisms. One of the study authors disclosed ties to the pharmaceutical industry, which warrants consideration when interpreting the results.