Insulin Autoimmune Syndrome

A 62-year-old woman who experienced a seizure was found to be hypoglycemic. A prolonged fasting test revealed raised critical insulin and C-peptide levels. CECT of the abdomen demonstrated an isodense focus in the tail of the pancreas. On the suspicion of insulinoma, she was referred for a 68 Ga-Exendin-4 PET/CT study, which revealed diffuse tracer uptake in the entire pancreatic tissue. She also underwent a 68 Ga-DOTATATE PET/CT scan, which demonstrated physiological uptake in the pancreas. She later tested positive for anti-insulin antibodies. We herein report a positive Exendin-4 PET/CT study in a case of insulin autoimmune syndrome with its uptake pattern in this entity.