Insulinoma Mimicking Psychiatric Illness: A Covert Endocrine Tumor

Insulinomas are rare neuroendocrine tumors with an annual incidence of four cases per million people in the general population. They have varied presentations making their diagnosis a challenging task necessitating a thorough patient assessment to ascertain early detection of this clinical entity by treating physicians. Insulinomas are characterized by the presence of Whipple's triad comprising of hypoglycemic symptoms, biochemical demonstration of hypoglycemia, and improvement of those symptoms after glucose administration. Biochemical detection of insulinoma by supervised 72-hour fasting test with plasma glucose, insulin, C-peptide, and proinsulin level measurements remains the gold standard of diagnosis. In this report, we present an interesting case of delayed diagnosis of pancreatic insulinoma. He was treated for more than six years as a psychiatric illness before receiving the correct diagnosis and treatment. Herein, a middle-aged man with a history of recurrent episodes of altered talk and confusion that resolved after eating something sweet. Biochemical investigations were suggestive of endogenous hyperinsulinemia. Pancreatic insulinoma was localized by a computed tomography scan. The patient underwent surgical resection of the tumor with complete resolution of his symptoms.