A Five-Year Journey to Diagnosis: Resolving Persistent Hypoglycemia Through Successful Insulinoma Resection-A Case Report.

Insulinoma is a rare functional pancreatic neuroendocrine tumor with an annual prevalence of 0.5-5 cases per million. It is characterized by excessive insulin secretion, leading to recurrent hypoglycemia, often diagnosed through Whipple's triad: hypoglycemic symptoms, documented low plasma glucose, and symptom resolution after glucose administration. Approximately 90% of insulinomas are sporadic, while 10% are associated with multiple endocrine neoplasia type 1. Diagnosis is frequently delayed due to nonspecific symptoms and misattributions to neurological or psychiatric conditions. Biochemical confirmation through a supervised fasting test and advanced imaging modalities, including CT, MRI, and endoscopic ultrasound (EUS), is essential for identifying and localizing the tumor. We report the case of a 52-year-old male who presented with a 5-year history of recurrent fasting and postprandial hypoglycemic episodes, including adrenergic and neuroglycopenic symptoms such as palpitations, diaphoresis, dizziness, and episodes of altered sensorium. Initial evaluations misattributed his symptoms to neurological and cardiac disorders, delaying diagnosis. Upon presentation, Whipple's triad was confirmed, and biochemical testing revealed hyperinsulinemic hypoglycemia (plasma glucose: 27 mg/dL, serum insulin: 45.83 mIU/L, C-peptide: 7.03 ng/mL). Imaging identified a 3 × 3 cm hypervascular lesion in the pancreatic tail. The patient underwent distal pancreatectomy, and histopathological analysis confirmed a grade 1 neuroendocrine tumor. Postoperative outcomes were favorable, with complete resolution of symptoms and normalization of glucose and insulin levels. Follow-up showed no recurrence of hypoglycemia. This case underscores the challenges in diagnosing insulinoma due to nonspecific symptoms and highlights the importance of Whipple's triad, biochemical tests, and imaging in timely diagnosis. Surgical resection remains the definitive treatment, with excellent long-term outcomes when performed promptly.