To eat, or not to eat… dietary patterns and the clinical recognition of insulinoma: a case report

Abstract Objectives Insulinoma is a rare pancreatic neuroendocrine tumor causing endogenous hyperinsulinemic hypoglycemia. Its heterogeneous clinical presentation often delays diagnosis. Dietary patterns, particularly ketogenic or high-carbohydrate regimens, may influence glucose homeostasis and modify the clinical manifestations of insulinoma. Case presentation A 70-year-old woman was admitted with recurrent documented hypoglycemia. She reported a 10-year history of seizure-like episodes and intermittent neurological symptoms that began after starting a ketogenic diet. Symptoms later became less frequent during a high-calorie, carbohydrate-rich diet but recurred after adopting a Mediterranean diet. Biochemical evaluation confirmed endogenous hyperinsulinemic hypoglycemia. A supervised fasting test documented symptomatic hypoglycemia with plasma glucose of 17 mg/dL, fulfilling Whipple’s triad. Magnetic resonance imaging revealed a 4 cm pancreatic tail lesion, and ˆ68 Ga-DOTATATE PET/CT showed intense uptake consistent with a somatostatin receptor-positive neuroendocrine tumor. As the patient declined surgery, diazoxide and dietary modifications were started, improving symptoms and glycemic control. Conclusions This case suggests that dietary habits may influence the clinical presentation of insulinoma. Marked carbohydrate restriction may unmask hypoglycemia, whereas high-carbohydrate intake may attenuate symptoms and contribute to delayed diagnosis. Careful assessment of dietary habits should be part of the evaluation of patients with recurrent unexplained hypoglycemia suggestive of insulinoma.