GLP1R and pancreatic insulinoma: Nevertheless, GLP-1R-based functional imaging has some limitations that may lead to a false negative exam, such as localization of the insulinoma in the pancreatic tail near the left kidney (site of physiological tracer’s excretion), false interpretation of the pancreaticoduodenal region uptake (falsely interpreted as physiological uptake in Brunner glands), or low expression of GLP-1R (especially in the malignant insulinoma subtype) [91,92].