Hypoglycaemia is common among hospital inpatients and is most often iatrogenic in nature and mediated by excessive or inappropriate insulin therapy or sulphonylurea use. Hypoglycaemia is a distinctly uncommon entity in people without diabetes. Endogenous hyperinsulinism is a rare but important cause of hyperinsulinaemic hypoglycaemia, which can prove difficult to diagnose and manage.
We describe a case of in a 72 year old man, who initially presented with biventricular cardiac failure and developed recurrent, severe hypoglycaemia, which was insulin-dependent in nature. His medical history was significant for oesophageal adenocarcinoma treated with Ivor-Lewis oesophagectomy 4 years prior. Despite extensive investigations including functional imaging and localisation with a calcium stimulation study, the cause was not identified. Non-insulinoma pancreatogenous hypoglycaemia syndrome (NIPHS) was suspected. The patient experienced progressive, recurrent and severe hypoglycaemia resulting in hypoglycaemic seizures. Medical therapy including somatostatin analogues and diazoxide was ineffective or not tolerated. Ultimately the patient underwent a diagnostic laparoscopy, which proceeded to a distal pancreatectomy. The patient's hypoglycaemia resolved immediately post-operatively. Histopathology of the resected pancreatic tissue revealed diffuse beta-cell hyperplasia consistent with a diagnosis of NIPHS. The patient was cured of his hypoglycaemia and remains well 18 months after surgery.
NIHPS is a very rare disorder characterised by endogenous hyperinsulinaemic hypoglycaemia due to proliferation of pancreatic beta islet cells and is a disease entity distinct from insulinoma, post gastric bypass hypoglycaemia and nesidioblastosis; the latter being a common cause of congenital hyperinsulinism in infants due to mutations in a number of genes governing beta cell function and insulin secretion. Limited case reports suggest adults with NIHPS usually have no prior history of hypoglycaemia, are male with normal BMI and have a history of non-bypass upper gastrointestinal surgery. The aetiology of the disorder in adults remains unclear and needs further clarification.