Head-to-head asthma analysis finds no advantage for tirzepatide over semaglutide

A new study comparing tirzepatide and semaglutide in adults who have both asthma and type 2 diabetes found that the two drugs led to almost identical rates of asthma flare-ups over one year. The research was published September 7, 2026, in the Journal of Asthma and Allergy ^[1].

Researchers used the TriNetX US Collaborative Network, a database drawing on records from more than 65 US healthcare organizations, to compare adults with asthma and type 2 diabetes who started either drug between June 2022 and December 2024, with follow-up through December 2025 ^[1]. Using a statistical method called propensity score matching, which pairs patients with similar health profiles, the team matched 8,176 patients taking tirzepatide with 8,176 taking semaglutide ^[1].

Over 12 months, 11.0% of tirzepatide patients had an asthma exacerbation, compared with 11.1% of semaglutide patients, a difference the researchers called statistically insignificant (hazard ratio 1.00, 95% confidence interval 0.91 to 1.10) ^[1]. The result held up across additional sensitivity and subgroup checks ^[1].

On secondary measures, tirzepatide users had a slightly lower rate of prescriptions for short-acting beta-agonists, the rescue inhalers used during an asthma attack, than semaglutide users (hazard ratio 0.92, 95% CI 0.88 to 0.96) ^[1]. But the two drugs showed a similar risk of needing systemic corticosteroids, the stronger anti-inflammatory drugs used for severe flares (hazard ratio 1.01, 95% CI 0.96 to 1.05) ^[1].

The researchers had expected tirzepatide to outperform semaglutide. Tirzepatide acts on two gut hormone receptors, GIP and GLP-1, while semaglutide acts on GLP-1 alone, and earlier lab research suggested this dual action might further calm airway inflammation ^[1]. The study authors note that asthma and type 2 diabetes often occur together, affecting roughly 13% to 16% of people with asthma, and that people with both conditions tend to have worse asthma control and more frequent flare-ups than those with asthma alone ^[1]. That backdrop is why researchers thought a stronger metabolic drug might also help breathing. This study did not confirm that idea for the main outcome of exacerbations ^[1].

Why it matters for patients

For people managing both asthma and type 2 diabetes, this study suggests that switching to tirzepatide over semaglutide, or vice versa, is unlikely to change the odds of having an asthma flare-up over the following year, based on real-world data ^[1]. The modestly lower rescue-inhaler use seen with tirzepatide was a secondary finding and did not extend to reduced use of corticosteroids, the treatment typically reserved for more severe exacerbations ^[1].

It is also important to understand what kind of evidence this is. The data come from retrospective health records, not a randomized controlled trial, so they show an association between drug choice and outcomes rather than direct proof that either drug causes more or fewer flare-ups ^[1]. The study authors themselves call for randomized trials to clarify whether any GLP-1-based therapy meaningfully affects asthma control in people who have both asthma and type 2 diabetes ^[1].

What happens next

The study authors say further investigation through randomized controlled trials is needed to clarify whether GLP-1 receptor agonist–based therapies play any role in asthma outcomes for people with type 2 diabetes ^[1]. The source does not name a specific planned trial or date for such research.