Researchers at Imperial College London ran four parallel analyses of UK electronic medical records — each covering 20,000 to 22,000 adults — comparing people who started a GLP-1 receptor agonist against people who started a sulfonylurea. Semaglutide carried the strongest signal in the set: close to 40% fewer asthma attacks and roughly 20% fewer COPD flare-ups. The work was presented on September 7, 2026 at the European Respiratory Society Congress in Barcelona by Dr Bohee Lee, with Professor Chloe Bloom of the National Heart & Lung Institute as lead investigator.
The number travelled fast because it lands on a gap nobody has filled. Asthma and COPD outcomes have never been prespecified endpoints in the large GLP-1 cardiovascular trials, so the entire respiratory signal for this drug class has been assembled after the fact from claims databases and medical records. Bloom's own framing was deliberately narrow: the findings are "encouraging, but they should not change treatment decisions on their own," and she cautioned against starting a GLP-1 for respiratory reasons outside current prescribing guidelines. What follows is what the presented data says, what the already-published record around it says, and where the whole thing is still guessing.
Research-context information only. Semaglutide, tirzepatide and liraglutide are active ingredients in FDA-approved prescription products; the research-peptide and compounded forms discussed and linked below are not FDA-approved and are sold for research purposes only. None of these compounds is approved to treat asthma, COPD, or any respiratory condition, and no regulator has reviewed a respiratory indication for any of them. Protocols, doses, and reactions described come from published research and self-reported community sources. Possession or use of investigational drugs outside an authorized clinical trial may be illegal in your jurisdiction. This article reports what has been documented, not what should be done. Consult a licensed physician for personal medical decisions.
What was presented in Barcelona
The design is a comparative new-user cohort, which matters more than the headline percentage. Rather than comparing GLP-1 users against people on nothing — a comparison that mostly measures who gets prescribed drugs — the Imperial group compared them against people starting a different diabetes drug at the same point in their treatment pathway. Sulfonylureas are the older, cheaper second-line option, and using them as the reference arm strips out a large slice of the "people who get new drugs are different" problem.
| Element | What was reported |
|---|---|
| Data source | UK electronic medical records |
| Design | Four parallel cohort analyses |
| Size | 20,000–22,000 adults per analysis |
| Exposure | GLP-1 receptor agonist initiation (all agents; semaglutide analysed separately) |
| Comparator | Sulfonylurea initiation |
| Asthma result | Semaglutide associated with ~40% fewer asthma attacks |
| COPD result | Semaglutide associated with ~20% fewer COPD exacerbations |
| Status | Conference presentation, ERS Congress Barcelona, September 7, 2026 — not yet peer-reviewed |
Dr Alexander Mathioudakis, who chairs the ERS Group on Airway Pharmacology and was not involved in the work, called it "one of the largest real-world studies to investigate GLP-1 receptor agonists and airways disease." That is the fair reading of its contribution: scale and a sensible comparator, not causal proof.
The asymmetry between the two numbers is worth sitting with. A 40% relative reduction in asthma attacks against a 20% reduction in COPD flare-ups is consistent with the rest of this literature, where asthma — a more inflammatory, more obesity-linked, more reversible condition — keeps showing larger effects than COPD, which is dominated by irreversible structural damage and smoking history.
The published record this lands on
The ERS abstract is not an outlier. It is the largest entry in a body of published work that has been pointing the same direction for two years, and the peer-reviewed numbers are more modest than the headline.
The biggest published cohort. A multinational retrospective study in Pharmacotherapy (September 2026) pulled 100,746 adults with both asthma and type 2 diabetes from the TriNetX Global Collaborative Network — 61,955 starting a GLP-1 receptor agonist, 38,791 starting an SGLT-2 inhibitor — then propensity-matched 28,831 to a side. Over six months, GLP-1 initiation was associated with a hazard ratio of 0.88 (95% CI 0.85–0.91) for first asthma exacerbation, 0.89 for asthma symptoms, and 0.79 for systemic corticosteroid use. The steroid number is the most clinically legible one in the whole field. Critically, the exacerbation association disappeared when follow-up was extended to one year — HR 0.95 (95% CI 0.89–1.02) (PMID 42618217).
The randomised-trial synthesis. A dose-stratified network meta-analysis in EClinicalMedicine (July 2026) pooled 128 randomised trials and 316,832 adults, looking at trial-reported asthma-COPD overlap events. Injectable semaglutide came in at RR 0.64 (95% CI 0.49–0.84) versus control — the only GLP-1 to separate from control in the analysis — alongside three SGLT-2 inhibitors. Semaglutide's signal sat specifically on the COPD side. One agent moved the other way: saxagliptin, a DPP-4 inhibitor, was associated with higher asthma risk at RR 2.09 (95% CI 1.01–4.33) (PMID 42376494).
The small, sharp comparison. A territory-wide Hong Kong cohort compared add-on GLP-1 receptor agonist against add-on DPP-4 inhibitor in 3,295 adults with co-existing asthma and diabetes — 76.8% of them at GINA steps 3 to 5, so moderate-to-severe disease. The GLP-1 arm showed a mean ratio of 0.513 for hospitalised asthma exacerbation, 0.343 for unscheduled outpatient visits requiring oral corticosteroids, 0.378 for emergency visits, and 0.419 for all exacerbations. The effect sizes are the largest in the literature — and the GLP-1 arm was 102 patients against 3,193 on the comparator (PMID 42516533).
The systematic review. The Journal of Allergy and Clinical Immunology: In Practice published a synthesis in September 2026 covering observational, clinical and preclinical evidence. Its conclusion: GLP-1 use was "consistently associated with reduced asthma exacerbations and health care utilization, predominantly in populations with obesity and/or type 2 diabetes," with several studies reporting associations that survived adjustment for BMI or glycaemic markers — but human data remain "limited by confounding and population selection," and airway-intrinsic evidence is "largely preclinical" (PMID 42167405).
What the design can and cannot carry
Four structural limits sit under every number above, and none of them is fixed by adding more records.
- Every result is in people with diabetes. The exposure in these studies is a diabetes prescription. The cohorts are older, heavier, and more medicated than the population searching for research-grade material, and the comparator is always another glucose-lowering drug. Nothing here describes what happens in a metabolically healthy adult with asthma.
- The effect is time-sensitive in the one dataset that tested it. A hazard ratio of 0.88 at six months that becomes 0.95 at twelve months is a pattern consistent with an early, possibly transient effect — or with differential dropout, since GLP-1 discontinuation rates in real-world cohorts routinely run 30% or higher.
- Confounding by indication is not eliminated by an active comparator, only reduced. In the UK and Hong Kong systems, the patient who gets a newer, more expensive injectable is systematically different from the one left on a sulfonylurea or a DPP-4 inhibitor — better engaged with care, more likely to attend reviews, more likely to have their inhaler technique corrected. Fewer exacerbations follow from that regardless of pharmacology.
- Conference abstracts move on peer review. The 40% figure is presented data, not a published paper. Effect sizes in this field have a history of shrinking between the podium and the journal.
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