If an insulinoma is strongly suspected but not revealed by the aforementioned modalities, additional functional imaging methods include somatostatin receptor imaging [Octreoscan® or 68Ga-DOTATOC/68Ga-DOTATATE/68Ga-DOTANOC positron emission tomography (PET)/CT] and glucagon-like peptide-1 (GLP-1) imaging [68Ga-DOTA-exendin-4 PET/CT]. Here, GCG is linked to pancreatic insulinoma.