The growing use of GLP-1 receptor agonists may affect cancer patients’ care because the drugs can influence results from FDG PET-CT scans, according to new research presented this week at the 38th Annual Congress of the European Association of Nuclear Medicine (EANM’25). These drugs mimic the natural GLP-1 hormone to reduce appetite, delay gastric emptying, and regulate blood sugar levels.
GLP-1 receptor agonists are now widely prescribed for individuals with type 2 diabetes and weight loss, with a 700% increase in usage reported in the United States between 2019 and 2023. Approximately 13% of U.S. adults are estimated to have used a GLP-1 agonist, representing about one in eight people in this country alone. The use of these drugs, such as Ozempic and Wegovy, has dramatically increased in recent years.
The global GLP-1 agonist market size was approximately $53.5 billion in 2024 and is projected to reach around $157 billion by 2030. Growth is driven by the increasing prevalence of type 2 diabetes and obesity, alongside the strong clinical efficacy and growing availability of GLP-1 receptor agonists.
The International Diabetes Federation (IDF) reported that 589 million adults had diabetes in 2024, a figure projected to reach 700 million by 2045. The World Health Organization reported that in 2022 one in eight people in the world were living with obesity—2.5 billion adults (18 years and older) were overweight. Worldwide adult obesity has more than doubled since 1990.
In this report, researchers from Alliance Medical Ltd. performed a retrospective case series review of oncologic FDG PET-CT scans in patients taking GLP-1 agonists. They observed several atypical patterns of tracer uptake that could be misinterpreted as pathology if a patient’s medication history is not considered.
“We noticed unusual uptake in one of our patients on a GLP-1 agonist, which prompted a wider review across our network. We found that these altered patterns are increasingly common, yet there is currently no national or international guidance in the U.K. addressing this emerging issue,” said Peter Strouhal, MBBS, lead author and medical director at Alliance Medical Ltd.
Misinterpreting these uptake patterns can lead to unnecessary investigations, inappropriate cancer staging and delays in treatment, which may cause stress and uncertainty for patients. “Recognizing the characteristic uptake associated with GLP-1 agonists helps avoid unnecessary anxiety and interventions, ensuring patients receive the right care, at the right time, without detours or doubt,” Strouhal added.
At present, the researchers do not recommend altering patient preparation or stopping GLP-1 agonists prior to FDG PET-CT scans. Instead, they advise that imaging teams carefully document patients’ medication histories to inform interpretation while formal guidance is developed. Current U.K. guidelines do not address this issue, although Australian guidance suggests continuing treatment, fasting from midnight, scheduling morning scans and ensuring good glucose control.
The research group intends to extend their data collection across additional imaging centers to provide a stronger evidence base for future national guidance. They also aim to establish international collaborations so that patients everywhere benefit from consistent and reliable PET-CT interpretation.
