Ozempic and other GLP-1 weight-loss drugs have become a sensation in recent years, helping millions shed pounds while also managing blood sugar. But new research shows these popular medications may have unexpected consequences beyond the well-known side effects like nausea, sulfurous burps, fatigue, or gastrointestinal changes. A recent study presented at the 38th Annual Congress of the European Association of Nuclear Medicine highlights that GLP-1 drugs can interfere with PET-CT scans, a crucial tool for detecting cancer and inflammatory diseases. This interference can mask serious conditions or make healthy tissue appear abnormal, potentially delaying life-saving diagnoses or leading to unnecessary tests and treatments.
How Ozempic works to lose weight
Originally developed to treat Type 2 diabetes, GLP-1 medications such as Ozempic, Wegovy, and Mounjaro mimic a natural hormone that regulates blood sugar and appetite. They increase insulin production, slow digestion, and promote a feeling of fullness, helping users lose weight effectively. In addition to aiding weight loss, these drugs have metabolic benefits, such as improving glycemic control, reducing insulin resistance, and lowering the risk of diabetes-related complications. However, the same mechanisms that make GLP-1 drugs effective also alter cellular metabolism and uptake of glucose-like tracers used in medical imaging. This unexpected interaction can create unusual “hot spots” on PET-CT scans, confusing radiologists and potentially masking or mimicking disease.
The PET-CT scan connection
PET-CT scans combine two powerful imaging tools: the PET scan shows metabolic activity in cells, while the CT scan provides detailed anatomical images of organs and tissues. PET scans use a radioactive tracer called FDG, which is absorbed more by cells with higher metabolic rates, such as cancerous or inflamed cells. CT scans map the physical structure of the body, allowing physicians to locate abnormalities precisely. When these images are combined, PET-CT provides a comprehensive picture that helps detect early-stage cancers and track treatment responses. However, GLP-1 medications like Ozempic can alter FDG absorption patterns, causing unusual tracer distribution that may appear as false positives or mask real abnormalities. This makes interpretation more challenging and may delay or complicate diagnoses.
Risks of misinterpreted scans
Doctors have observed that patients on GLP-1 medications often show altered PET-CT scan results. These changes can resemble abnormal growths or inflammation even when none exist, potentially prompting unnecessary biopsies, repeated scans, or invasive procedures. Misinterpretation of scans may also lead to incorrect cancer staging, impacting treatment plans and prognosis. With about 12% of U.S. adults using these drugs, the problem is becoming increasingly common. Experts warn that the lack of formal guidelines on interpreting scans for GLP-1 users could result in increased patient anxiety, avoidable healthcare costs, and dangerous delays in detecting serious diseases.
For now, researchers do not recommend stopping GLP-1 medications before PET-CT imaging. Instead, they emphasize careful documentation of medication history for all patients undergoing scans. Radiologists and clinicians are advised to account for GLP-1 use when interpreting results to avoid false positives and misdiagnoses. Strouhal and his colleagues are expanding their data collection across multiple imaging centers and collaborating internationally to establish evidence-based protocols. Their goal is to create standardized guidelines for safely and accurately interpreting PET-CT scans in patients taking these widely used drugs, ensuring that imaging remains a reliable tool for early disease detection.
What patients should know
Patients using GLP-1 drugs should proactively inform their doctors and imaging centers about their medication. While these drugs remain safe and effective for weight loss and diabetes management, understanding their impact on PET-CT scans is critical. Being aware of these interactions helps physicians plan tests appropriately, interpret results correctly, and reduce unnecessary stress or procedures. Patients should continue following prescribed treatments while maintaining open communication with healthcare providers.
How Ozempic works to lose weight
Originally developed to treat Type 2 diabetes, GLP-1 medications such as Ozempic, Wegovy, and Mounjaro mimic a natural hormone that regulates blood sugar and appetite. They increase insulin production, slow digestion, and promote a feeling of fullness, helping users lose weight effectively. In addition to aiding weight loss, these drugs have metabolic benefits, such as improving glycemic control, reducing insulin resistance, and lowering the risk of diabetes-related complications. However, the same mechanisms that make GLP-1 drugs effective also alter cellular metabolism and uptake of glucose-like tracers used in medical imaging. This unexpected interaction can create unusual “hot spots” on PET-CT scans, confusing radiologists and potentially masking or mimicking disease.
The PET-CT scan connection
PET-CT scans combine two powerful imaging tools: the PET scan shows metabolic activity in cells, while the CT scan provides detailed anatomical images of organs and tissues. PET scans use a radioactive tracer called FDG, which is absorbed more by cells with higher metabolic rates, such as cancerous or inflamed cells. CT scans map the physical structure of the body, allowing physicians to locate abnormalities precisely. When these images are combined, PET-CT provides a comprehensive picture that helps detect early-stage cancers and track treatment responses. However, GLP-1 medications like Ozempic can alter FDG absorption patterns, causing unusual tracer distribution that may appear as false positives or mask real abnormalities. This makes interpretation more challenging and may delay or complicate diagnoses.
Risks of misinterpreted scans
Doctors have observed that patients on GLP-1 medications often show altered PET-CT scan results. These changes can resemble abnormal growths or inflammation even when none exist, potentially prompting unnecessary biopsies, repeated scans, or invasive procedures. Misinterpretation of scans may also lead to incorrect cancer staging, impacting treatment plans and prognosis. With about 12% of U.S. adults using these drugs, the problem is becoming increasingly common. Experts warn that the lack of formal guidelines on interpreting scans for GLP-1 users could result in increased patient anxiety, avoidable healthcare costs, and dangerous delays in detecting serious diseases.
For now, researchers do not recommend stopping GLP-1 medications before PET-CT imaging. Instead, they emphasize careful documentation of medication history for all patients undergoing scans. Radiologists and clinicians are advised to account for GLP-1 use when interpreting results to avoid false positives and misdiagnoses. Strouhal and his colleagues are expanding their data collection across multiple imaging centers and collaborating internationally to establish evidence-based protocols. Their goal is to create standardized guidelines for safely and accurately interpreting PET-CT scans in patients taking these widely used drugs, ensuring that imaging remains a reliable tool for early disease detection.
What patients should know
Patients using GLP-1 drugs should proactively inform their doctors and imaging centers about their medication. While these drugs remain safe and effective for weight loss and diabetes management, understanding their impact on PET-CT scans is critical. Being aware of these interactions helps physicians plan tests appropriately, interpret results correctly, and reduce unnecessary stress or procedures. Patients should continue following prescribed treatments while maintaining open communication with healthcare providers.
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