INTRODUCTION
Insulinoma, a prevalent functional pancreatic neuroendocrine tumor (pNET), is characterized by specific insulin secretion, leading to endogenous hyperinsulinemia and subsequently resulting in hypoglycemia.[1] Insulinoma is the predominant cause of hypoglycemia related to endogenous hyperinsulinemia, which occurs in approximately 1 to 4 individuals per million.[2] The primary clinical manifestations of insulinoma include spontaneous hypoglycemia, psychiatric abnormalities, and neurological symptoms such as impaired consciousness and seizures.[3] While qualitative diagnosis of insulinoma is straightforward, the challenge lies in localizing the often small and hidden tumor. Some patients, despite traditional imaging, remain undiagnosed or are misdiagnosed. Herein, in this report, we present a case of insulinoma with an occult tumor and provide a comprehensive review of the relevant literature, aiming to raise awareness among clinicians regarding early diagnosis and treatment of insulinoma.