Optimal Management of Insulin in Patients Undergoing 18F-Fluorodeoxyglucose Positron Emission Tomography Scans

The management of insulin injections and insulin pumps before 18F-fluorodeoxyglucose-positron emission tomography integrated computerized tomography (FDG-PET/CT) scans is an important area to investigate given the rising rate of diabetes, the significant association between diabetes and cancer, and the complex relationship among glucose, insulin, and FDG tumor uptake. The purpose of this study was to determine the recommendations around subcutaneous insulin administration, insulin pumps, and hybrid closed-loop systems before FDG-PET scans.

We examined the websites of 100 hospitals selected from the 2022 US News and World Report top cancer hospitals for specific strategies around diabetes medication management before FDG-PET/CT scans.

Of the 100 hospital websites, 61 had instructions addressing patients with diabetes. Of the 61 hospitals, 47.5% (n = 29) referred patients to their provider for further instructions, 18% (n = 11) referred patients to their own internal radiology department for further instructions, 16.4% (n = 10) had instructions on oral diabetic medications, 23% (n = 14) had instructions on insulin, and 3.3% (n = 2) had instructions on insulin pump management. Most commonly, instructions were to stop insulin 3 to 4 hours before the study and direct patients to their referring provider for more detailed instructions (n = 7).

There is a lack of guidance and consensus among US cancer hospitals on managing insulin and continuous subcutaneous insulin infusions before FDG-PET/CT studies and a majority rely on referring providers to advise patients. However, society guidelines offer inconsistent recommendations and little research has been carried out to help guide referring providers. A multidisciplinary panel of specialists could help to guide practitioners on optimal management.