Insulinoma

An insulinoma is a neuroendocrine tumour deriving mainly from pancreatic Islets of Langerhans cells

Basics

• most common pancreatic endocrine tumour
• 10% malignant, 10% multiple
• of patients with multiple tumours, 50% have MEN-1

Features

• of hypoglycaemia: typically early in morning or just before meal, e.g. diplopia, weakness etc
• rapid weight gain may be seen
• high insulin, raised proinsulin:insulin ratio
• high C-peptide

Diagnosis

• supervised, prolonged fasting (up to 72 hours)
• CT pancreas

Management

• surgery
• diazoxide and somatostatin if patients are not candidates for surgery