Abstract
An insulinoma is a pancreatic tumor that secretes excessive quantities of insulin that cause hypoglycemia. However, insulinoma is difficult to definitively diagnose in primary care practice. A previous study reported a median period of 2 years before an insulinoma was definitively diagnosed. A large number of patients with insulinomas present with neurological symptoms; thus, patients may be misdiagnosed and receive treatment for mental illness or epilepsy. Patients with prolonged hypoglycemia may progress without typical symptoms of hypoglycemia. Early diagnosis of the disease is possible by detailed inquiry and review of past medical examination data with which no symptom of the disease was detected. We report the case of a 43-year-old man who presented with recurrent transient amnesia and received an appropriate early differential diagnosis and prompt surgical treatment for insulinoma.