In the largest published case series, 11 adults with cystic fibrosis treated with GLP-1 agonists experienced weight loss (median 7.2 kg), improved lung function in most, and a 31.5% reduction in daily insulin dose for those with CF-related diabetes.
31.5% less insulin neededAll CF patients with diabetes reduced daily insulin while on GLP-1 therapy, with most also showing improved lung function
What the researchers found
All 11 CF patients lost weight (median -7.2 kg). 8/11 improved FEV1 (up to +18%), 9/11 improved FVC (up to +26%). All 7 with CFRD reduced insulin (mean -31.5% total daily dose). Glucose time in range improved (mean +11%).
Why it matters
As CF life expectancy increases, more patients face obesity and CF-related diabetes. This first substantial report shows GLP-1 drugs may address both while unexpectedly improving lung function—a critical finding for a disease where lung decline is the primary driver of mortality.
The numbers in context
11 patients (3 male, 7 female, ages 24-47, BMI 25.7-43.7). 9 on semaglutide, 2 on tirzepatide. Duration 1-50 months. Median weight loss 7.2 kg. BMI change -0.9 to -8.1. FEV1 improved in 8 of 11 (change -5 to +18). FVC improved in 9 of 11 (change +1 to +26). Mean insulin reduction 31.5%. 4 discontinued.
How the study worked
Retrospective case series of 11 adults with CF (3 male, 7 female, age 24-47, BMI 25.7-43.7) treated with GLP-1 agonists (semaglutide or tirzepatide) for 1-50 months at a single CF center.
Who was studied
Adults with cystic fibrosis treated with GLP-1 agonists
What this study cannot tell us
Very small case series (n=11) without controls. Retrospective design. Single center. Variable treatment duration (1-50 months). Lung function improvements could be confounded by other treatments. 4/11 (36%) discontinued, raising tolerability concerns.
How to read the evidence
Case series (lowest level of clinical evidence) but the largest published on this topic. Provides important hypothesis-generating data that warrants controlled trials.
When this study was published
Published in 2025; addresses the emerging intersection of CF metabolic complications and GLP-1 therapy.
The bigger picture
CF treatment has been revolutionized by CFTR modulators like elexacaftor/tezacaftor/ivacaftor, but weight gain and metabolic complications are emerging side effects. GLP-1 drugs could become an important complementary therapy, addressing obesity and diabetes while potentially supporting lung health.
Questions still open
- Why did lung function improve—is it due to weight loss reducing chest wall restriction, or a direct anti-inflammatory effect?
- Are GLP-1 drugs safe for CF patients with lower BMIs who may lose too much weight?
- Would a controlled trial confirm these lung function benefits in CF?
Common questions
Can people with cystic fibrosis take GLP-1 drugs like semaglutide?
Why might GLP-1 drugs improve lung function in CF?
Read the original research
Glucagon-like-peptide-1 agonist therapy in adults with cystic fibrosis.
Journal of cystic fibrosis : official journal of the European Cystic Fibrosis Society, 24(1), 40-46
Citation
Park, Sanghoon; Jain, Raksha; Mirfakhraee, Sasan. (2025). Glucagon-like-peptide-1 agonist therapy in adults with cystic fibrosis.. Journal of cystic fibrosis : official journal of the European Cystic Fibrosis Society, 24(1), 40-46. https://doi.org/10.1016/j.jcf.2024.08.005