GLP-1 drugs are reshaping weight loss—and now imaging, too
GLP-1 receptor agonists, best known by brand names like Ozempic, Wegovy, and Mounjaro, have surged in popularity for their powerful weight‑loss effects. But as their use has exploded—driven by a 700% rise in the United States from 2019 to 2023—so too have reports of unusual side effects. A new set of findings from researchers across Europe suggests that these medications may also interfere with a critical medical tool: PET‑CT scans, which doctors rely on to detect cancer and inflammatory diseases.
How GLP-1 meds work—and what that means for imaging
GLP‑1 medications mimic a natural hormone that helps regulate blood sugar and appetite. In addition to slowing digestion and boosting insulin production, these drugs can drive significant biological changes. PET‑CT imaging, however, depends on detecting cells that take up a radioactive tracer (FDG) used to highlight areas of high metabolic activity — typically cancerous cells or inflamed tissue. When patients are on GLP‑1 therapies, researchers are seeing unusual FDG uptake patterns that can resemble disease or obscure real problems.
“We noticed unusual uptake in one of our patients on a GLP‑1 agonist, which prompted a wider review across our network,” said Dr. Peter Strouhal, medical director at Alliance Medical Ltd in the UK and lead author of the study. “We found that these altered patterns are increasingly common, yet there is currently no national or international guidance addressing this emerging issue.”
Why this matters for patients and clinicians
The implications are meaningful. Misreading FDG uptake can lead to unnecessary tests, incorrect cancer staging, or dangerous delays in treatment. As cancer rates rise, particularly among younger adults, accurate early detection remains essential. Experts emphasize that recognizing the characteristic uptake associated with GLP‑1 agonists helps prevent anxiety, overtreatment, and misdiagnosis while patients continue their therapy for weight management.
In the short term, imaging teams face a practical challenge: how to interpret PET‑CT results when a patient is using a GLP‑1 medication. The current study advocates for heightened awareness and documentation of medication histories to aid radiologists and clinicians until formal guidelines are established.
What doctors recommend now—and what’s next
At present, researchers do not advise patients stopping GLP‑1 medications before PET‑CT scans. The recommended path is to record the patient’s drug use and for imaging teams to factor this information into interpretation. The researchers are planning broader data collection across more imaging centers and international collaboration to develop robust guidelines that can be adopted globally.
Key takeaways for patients
- GLP‑1 meds like Ozempic, Wegovy and Mounjaro are linked to unusual PET‑CT uptake patterns in some patients.
- Accurate medication history is crucial for interpreting scans accurately.
- Do not stop medications without medical advice; discuss imaging plans with your clinician.
- Guidelines are under development, with international collaboration planned to standardize practice.
Looking ahead
Researchers plan to expand data collection across more imaging centers and pursue international cooperation to build stronger evidence. As GLP‑1 medications remain a popular option for weight management, establishing clear imaging guidelines will help protect patient safety and ensure timely, appropriate care for serious health conditions.
