Too low a blood glucose level is most often the result of an overdose of insulin, but another cause is also possible. This is an insulinoma (also known as an islet cell or insulinoma), which originates from a specific population of pancreatic islet cells and produces insulin in excess. What are the symptoms of an insulinoma, what tests are ordered when this lesion is suspected in a patient and what treatment is implemented in patients with an insulinoma?