A patient on a GLP-1 receptor agonist had abnormal muscle and heart uptake on an FDG PET scan, making the cancer scan difficult to interpret due to the drug's insulin-stimulating effects.
Nondiagnostic PET scanin a patient on a GLP-1 agonist, with abnormal muscle and heart uptake complicating cancer detection
What the researchers found
A patient taking a GLP-1 receptor agonist/insulin secretagogue had a nondiagnostic FDG PET scan showing abnormal muscular and myocardial FDG uptake. The altered biodistribution was attributed to the drug's insulin-stimulating mechanism, which redirects glucose uptake to muscle and heart tissue, potentially masking tumor uptake and complicating scan interpretation.
Why it matters
With tens of millions of people now taking GLP-1 drugs like semaglutide for diabetes and weight loss, this is a growing practical concern for cancer imaging. If a PET scan can't distinguish tumors from medication-related uptake, cancers could be missed or patients could need repeat scans. Nuclear medicine physicians and oncologists need to know about this interaction.
How the study worked
This is a clinical case report describing a single patient's FDG PET scan findings in the context of GLP-1 receptor agonist use. The authors analyzed the scan findings, attributed the altered FDG biodistribution to the medication's effect on insulin secretion, and reviewed the clinical implications for nuclear medicine practice.
What this study cannot tell us
This is a single case report, which is the lowest level of clinical evidence. The causal link between the GLP-1 drug and altered PET scan is presumptive, not definitively proven. Systematic studies with larger populations are needed to quantify how often this occurs and how significantly it affects scan diagnostic accuracy. The specific GLP-1 drug, dose, and timing relative to the scan are not detailed.
How to read the evidence
This is a single case report, providing the lowest level of clinical evidence. While it raises an important clinical awareness point, systematic studies are needed to establish the frequency and clinical impact of GLP-1 drug interference with PET imaging.
When this study was published
Published in 2024, this case report is timely given the rapid increase in GLP-1 drug prescriptions and the growing need to understand their effects on medical testing.
The bigger picture
This case highlights an underappreciated intersection between the GLP-1 drug revolution and diagnostic imaging. As GLP-1 receptor agonists become some of the most prescribed drugs worldwide, their effects on medical tests beyond their intended use need systematic study. This isn't just about PET scans — any test dependent on glucose metabolism could potentially be affected.
Questions still open
- Should patients be advised to pause GLP-1 drugs before PET scans, and for how long?
- How frequently does this interference actually affect clinical decision-making in practice?
- Do all GLP-1 receptor agonists equally affect FDG PET biodistribution, or does it vary by drug and dose?
Common questions
Should I stop my GLP-1 drug before a PET scan?
How do GLP-1 drugs interfere with PET scans?
Read the original research
FDG PET in a Patient on a GLP-1 Agonist/Insulin Secretagogue.
Clinical nuclear medicine, 49(9), e436-e438
Citation
Oldan, Jorge D; Landman, Paula G; Schroeder, Jennifer A; Khandani, Amir H; Solnes, Lilja B; Lee, Carrie B; Rowe, Steven P. (2024). FDG PET in a Patient on a GLP-1 Agonist/Insulin Secretagogue.. Clinical nuclear medicine, 49(9), e436-e438. https://doi.org/10.1097/RLU.0000000000005318