The rise in GLP-1 receptor agonist drugs prescribed for weight loss and type 2 diabetes may impair the interpretation of some cancer scans and throw doctors into the dark.
This is the discovery by UK-based researchers who discovered a drug known to alter glucose metabolism, stomach function and the body’s stress and energy systems, which may lead to a “unique uptake” pattern in FDG PET-CT scans.
This is a combined imaging technique used to identify areas of high metabolic activity, such as tumors or inflammation. The scan follows an injection of a radioactive form of glucose, which provides a signal picked up by the scanner.
Previous case reports have shown increased FDG uptake in skeletal muscle, cardiac muscle, and brown adipose tissue (fat that burns energy to generate heat), which may be mistaken for cancer or inflammatory disease.
In a new study from Alliance Medical Ltd – presented today at the 38th Annual Congress of the European Society for Nuclear Medicine – the team performed a retrospective case series review of these scans in patients taking GLP-1 agonists.
They observed several unusual patterns of “tracer uptake” (safe radioactive chemicals used to highlight disease) that could be misinterpreted as disease if the patient’s drug history was not taken into account.
Dr Peter Strouhal, medical director at the Alliance, said: “We noticed abnormal absorption in one of our patients on a GLP-1 agonist in one of our patients on a GLP-1 agonist. “We found this altered pattern to be increasingly common, but there is currently no national or international guidance in the UK addressing this emerging issue. doesn’t exist.”
However, the authors note that Australian guidelines mentioning the use of GLP-1 recommend continuous treatment, fasting from midnight, scheduling scans in the morning, and ensuring good glucose control.
“It is important that patients prepare for their FDG PET-CT scan by fasting as instructed (natural glucose levels in the blood are low and there is little uptake of radioactive glucose in the muscle due to resting after the injection). It is also important to prepare patients for their medical history, as other factors may affect it.” It may affect your medical history. treatment,” said Heather Williams, a consultant physicist in nuclear medicine at Christie’s who was not involved in the study. news week.
“This practice is consistent with (general) UK, European and US guidelines, including: Communications in Nuclear Medicine (UK), Oncology – EANM (Europe) and EANM/SNMMI FDG PET/CT: Guidelines for Tumor Imaging | FDG PET-CT Scans in Patients.”
Still, misinterpreting the scan patterns detected in this study could lead to unnecessary investigations, inappropriate cancer staging (which determines the size of the tumor and its activity), and delays in treatment, the researchers warned. As well as the medical implications, this can also cause stress for patients.
“Recognizing the characteristic uptake associated with GLP-1 agonists can help avoid unnecessary anxiety and interventions, and ensure patients receive the correct treatment without diversion or suspicion,” added Dr. Strouhal.
Currently, based on these findings, researchers recommend not altering patient preparation or discontinuing GLP-1 agonists prior to FDG PET-CT scanning. They urge imaging teams to carefully document the patient’s medication history to aid interpretation while formal guidelines are developed.
Researchers plan to extend the investigation across more imaging centers to provide evidence for more specific guidelines and collaborate internationally for the benefit of patients around the world.
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Updated 10/08/25, 06:16 AM ET: This article has been updated with additional information and comments from Heather Williams.
reference
Strouhal, P., Meadows, A., & McGovern, A. (2025). Heavy Matters: GLP-1 Agonists and Altered Images in FDG PET-CT. European Association for Nuclear Medicine (EANM) Annual Congress 2025.
