Insulinoma and Hypoglycaemia

Abstract

Hypoglycaemia is a clinical syndrome with diverse aetiologies. While the list of possible causes is extremely long, excluding patients with diabetes then the most frequent cause in patients who are otherwise well is an insulinoma. Insulinomas are the most common functioning pancreatic islet cell tumour and may be part of the multiple endocrine neoplasia type 1 syndrome. Patients present with episodic symptoms of neuroglycopaenia and catecholamine responses, and diagnosis is confirmed by evidence of endogenous hyperinsulinaemic hypoglycaemia with tumour localization by CT, MRI, endoscopic ultrasound, functional imaging, and/or intra-arterial calcium stimulation with venous sampling. Most tumours are benign and solitary, making surgical cure and long-term remission possible with complete resection. Diazoxide, everolimus, and somatostatin analogues are the major medical options for hormonal control in metastatic disease, while peptide receptor radionuclide therapy, chemotherapy, and liver-debulking procedures are reserved for the more aggressive tumours. Important differential diagnoses of hypoglycaemia without apparent causes include medications, non-insulinoma pancreatogenous hypoglycaemic syndrome, autoimmune hypoglycaemia, and non-islet cell tumour hypoglycaemia.