Endocrine Abstracts

Insulinomas are rare functional pancreatic neuroendocrine tumours, with an incidence of 1–4 per million people per year. The median age at diagnosis is 50–55 years; cases in patients over 80 are exceptionally uncommon. We report a 91-year-old man presenting with recurrent early-morning episodes of confusion, dizziness, slurred speech, and disinhibition. These episodes appear to have commenced following a COVID-19 illness. His first major episode resulted in a fall with a fracture of the ulna and documented hypoglycaemia, initially attributed to stroke and poor intake. His background medical history includes ischaemic heart disease, severe aortic stenosis with heart failure, angina, hypertension, epilepsy (absence seizures), and prior prostate cancer. Relevant medications include diltiazem, phenytoin and ramipril. His daughter later confirmed recurrent home glucose readings of ~2.2 mmol/l, often treated with honey. Approximately 2 years after the start of symptoms, he was admitted with vomiting, reduced responsiveness, and glucose was 1.8 mmol/l. supervised fast confirmed endogenous hyperinsulinemia (glucose 2.1 mmol/l, insulin 68 pmol/l, C-peptide 800 pmol/l, suppressed β-hydroxybutyrate, negative sulfonylurea screen). CT and MRI of pancreas demonstrated no specific lesion. No lesions were evident on a CT chest, abdomen and pelvis. A 68Ga-DOTATATE PET-CT localised an 8 mm avid lesion in the uncinate process adjacent to the superior mesenteric vein. Diazoxide (100 mg TDS) initially stabilised glycaemia but triggered fluid overload, leading to readmission. Octreotide 100 mg SC paradoxically worsened hypoglycaemia and was stopped. Low-dose diazoxide (50 mg BD) plus prednisolone (5 mg daily and 2.5 mg nocte) with dietary modification was initiated for him. Furosemide relieved fluid overload. Early-morning hypoglycaemia persisted. Given tumour proximity to the SMV and frailty, EUS ablation was not possible. Our case highlights the challenges in the diagnosis and management of an insulinoma in the elderly population. In this patient, age bias and attribution of early results to drug interference delayed a supervised fast, while symptoms resembling stroke and post-ictal seizures further clouded the diagnosis. Managing refractory insulinoma in the very elderly remains especially difficult. Our case also highlights the paradoxical hypoglycaemia with octreotide and the challenging side effects with diazoxide.