ABSTRACT
Neuropsychiatric symptoms are generally seen in patients with insulinoma and diagnosis may be established late because of misdiagnosis. A 54-yearold woman presented with drowsiness and unconsciousness developing especially in the morning, and it was learned that these symptoms resolved with feeding. Hypoglycemia was detected in the laboratory evaluation, and a prolonged supervised fasting test was done after hospitalization. Result of the insulin/c-peptid ratio was in accordance with insulinoma. Abdominal ultrasonography and magnetic resonance imaging did not demonstrate any tumor in pancreas. However, the localization of tumor was determined with endoscopic ultrasonography. Tumor in the head of pancreas was resected with enucleation method. Hypoglycemia was not detected in the postoperative follow-up period. That the patient initially admitted to the departments of neurology and psychiatry even in the presence of typical hypoglycemia symptoms led us to call attention to the importance of insulinoma diagnosis.