Advances in Diabetes Medications and Patient Preparation for Oncologic FDG PET: AJR Expert Panel Narrative Review

Preparation of patients with diabetes for oncologic [18F]FDG PET remains variable across institutions despite increasing diabetes prevalence and expanding use of emerging glucose-lowering medications and diabetes technologies. This AJR Expert Narrative Review examines effects of hyperglycemia and insulin exposure on [18F]FDG biodistribution and proposes preparation strategies for oncologic [18F]FDG PET. As few studies have systematically examined optimal approaches to glycemic control before [18F]FDG PET, the article integrates available literature with consideration of existing society guidelines in forming consensus-driven clinical guidance. Standard pre-examination practices include fasting, hydration, and avoidance of rapid- or short-acting insulin use. However, guidelines differ in serum glucose thresholds for patient triage, timing of insulin adjustments, and insulin pump recommendations. Additionally, limited guidance is available on SGLT-2 inhibitors, incretin-based therapies (e.g., GLP-1 receptor agonists), and automated insulin delivery systems. The panel supports standardized facility-level protocols, continued use of insulin pumps in basal mode, and general avoidance of correctional insulin immediately before imaging. A management algorithm incorporating point-of-care glucose assessment on patient arrival, relatively permissive glucose level thresholds, and approaches to avoid same-day cancellations is presented. Prospective studies are needed to evaluate the effects of individual glucose-lowering medication classes on [18F]FDG biodistribution and image quality.