Metformin may reduce asthma attacks

The glucose-lowering drug metformin appears to be associated with fewer asthma attacks, with further reductions when metformin is used in combination with GLP-1RAs, according to a study.

Researchers used hospital admissions and mortality data from the UK Clinical Practice Research Datalink (CPRD) Aurum. They estimated the association of metformin and add-on antidiabetic medications (GLP-1RA, DPP-4 inhibitors, sulphonylureas, SGLT2 inhibitors, and insulin) with asthma attacks using two distinct approaches: a self-controlled case series (SCCS) and a metformin new user cohort with inverse probability of treatment weighting (IPTW).

A total of 4,278 patients (mean age 52.9 years, 61.2 percent women) were included in the SCCS cohort and 8,424 patients (55.7 percent women) in the IPTW cohort (unexposed: mean age 61.6 years; exposed: mean age 59.7 years).

During the 12-month follow-up, the primary outcome of first asthma exacerbation (short course of oral corticosteroids, unscheduled asthma-related hospital attendance, or death) occurred less frequently with metformin users than nonusers, with the magnitude of effect similar in both SCCS (incidence rate ratio [IRR], 0.68, 95 percent confidence interval [CI], 0.62–0.75) and IPTW (hazard ratio, 0.76, 95 percent CI, 0.67–0.85). No evidence of significant bias was seen in negative control analyses.

The association between metformin and asthma attacks was not modified by factors such as haemoglobin A1c levels, BMI, blood eosinophil cell counts, and asthma severity.

GLP-1RA was the only add-on antidiabetic medication to have an additive association (SCCS: IRR, 0.60, 95 percent CI, 0.49–0.73).