{"entity":{"id":"idea-pu-sglt2-glp1-plan-before-pet","kind":"idea","name":"A written plan for SGLT2 inhibitors and GLP-1 medicines before an FDG PET-CT scan","aka":[],"tldr":"PET-CT scans for cancer measure how much sugar tissues take up, and many people now take newer diabetes and weight-loss medicines that change sugar handling. The main European guideline predates their wide use and says nothing about them, while reports suggest they can blur parts of the scan. There is no agreed advice on whether to pause them.","summary":"The guideline gap. The EANM FDG PET/CT procedure guideline (version 2.0, 2015), the reference for preparing adults, covers fasting, blood glucose, insulin and metformin but not sodium-glucose cotransporter 2 (SGLT2) inhibitors or glucagon-like peptide-1 (GLP-1) receptor agonists. A joint Australian Diabetes Society and Australian and New Zealand Society of Nuclear Medicine guideline for people with diabetes (summarised in 2026) covers oral glucose-lowering medicines; only its summary abstract was read, so what it advises for these classes is not reported here.\n\nWhat the reports show. In 262 women with breast cancer having FDG PET/CT, thyroid uptake was less frequent and lower in the 55 taking an SGLT2 inhibitor, independent of glucose control (Alanli 2026). In a propensity-matched oncology cohort of 187 pairs from 6,747 scans, heart uptake was absent in 64.7 per cent of those taking an SGLT2 inhibitor against 37.4 per cent of those not (Sperry 2025). For GLP-1 medicines the evidence is case reports: a same-day semaglutide injection was followed by diffuse muscle uptake that obscured lesions, which cleared on a scan after the drug had been stopped for 6 days (Hong 2026), and a second report describes muscle and heart uptake complicating interpretation (Oldan 2024). None of these studies tested a preparation rule.\n\nWhat this means. Whether to pause these medicines, for how long, and how that weighs against blood glucose on the day, is decided department by department.","asOf":"2026-11-11","links":[{"label":"Boellaard et al., FDG PET/CT: EANM procedure guidelines for tumour imaging, version 2.0 (European Journal of Nuclear Medicine and Molecular Imaging 2015)","url":"https://doi.org/10.1007/s00259-014-2961-x"},{"label":"Joint Australian Diabetes Society and Australian and New Zealand Society of Nuclear Medicine procedure guideline for FDG PET/CT imaging in patients with type 1 and type 2 diabetes (Internal Medicine Journal 2026)","url":"https://doi.org/10.1111/imj.70344"},{"label":"Alanli et al., Sodium glucose cotransporter 2 inhibitors may mask malignancy-associated fluorodeoxyglucose uptake in the thyroid on PET/CT (Revista da Associação Médica Brasileira 2026)","url":"https://doi.org/10.1590/1806-9282.20260904"},{"label":"Sperry et al., SGLT2 inhibitor treatment is associated with reduced cardiac glucose metabolism: a matched FDG-PET cohort study (JACC: Advances 2025)","url":"https://doi.org/10.1016/j.jacadv.2025.102016"},{"label":"Hong et al., Subcutaneous injection of semaglutide causes increased muscle uptake of 18F-FDG and reduces the imaging quality of PET/CT: a case report (EJNMMI Research 2026)","url":"https://doi.org/10.1186/s13550-026-01373-4"},{"label":"Oldan et al., FDG PET in a patient on a GLP-1 agonist/insulin secretagogue (Clinical Nuclear Medicine 2024)","url":"https://doi.org/10.1097/rlu.0000000000005318"}],"tags":["protocol-upgrade","upgrade:untested","evidence:insufficient","precision"],"related":[],"cancers":[],"sections":["imaging"],"technologies":["fdg-pet","pet-ct"],"targets":[],"drugs":[],"companies":[],"institutions":["eanm"],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":["b-knowledge-diffusion"],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"hypothesis":"A stated preparation rule for SGLT2 inhibitors and GLP-1 receptor agonists before FDG PET-CT (for example, timing of the last GLP-1 injection relative to the scan) reduces non-diagnostic or equivocal scans without unsafe blood glucose.","rationale":"Use of both classes has grown fast among people of the age at which cancer is staged; the signals that they alter FDG distribution are consistent across a cohort, a matched analysis and case reports, and a preparation rule costs nothing if it works.","test":"A prospective multicentre cohort recording drug, dose and timing against blinded image-quality scores and lesion conspicuity, followed by a randomised comparison of continuing against a timed pause for GLP-1 receptor agonists if the cohort shows an effect.","maturity":"speculative","actor":"clinic","cost":"small","horizonYears":3},"route":"/ideas/idea-pu-sglt2-glp1-plan-before-pet/","neighbours":{"section":[{"id":"imaging","kind":"section","name":"Imaging","route":"/fronts/imaging/"}],"technology":[{"id":"fdg-pet","kind":"technology","name":"FDG PET","route":"/technologies/fdg-pet/"},{"id":"pet-ct","kind":"technology","name":"PET/CT","route":"/technologies/pet-ct/"}],"institution":[{"id":"eanm","kind":"institution","name":"European Association of Nuclear Medicine","route":"/institutions/eanm/"}],"bottleneck":[{"id":"b-knowledge-diffusion","kind":"bottleneck","name":"Knowledge reaches practice too slowly","route":"/bottlenecks/b-knowledge-diffusion/"}],"protocol":[{"id":"fdg-pet-ct-preparation","kind":"protocol","name":"FDG PET-CT scan preparation: fasting, blood glucose and diabetes","route":"/protocols/fdg-pet-ct-preparation/"}]}}