A 42-year-old woman presented to her GP with episodes of feeling shaky exacerbated by physical exercise and prolonged fast. She was previously diagnosed with an insulinoma in 2006 (serum glucose 1.6 mmol/l, serum insulin 3.1 mIU/l and serum C-peptide <165 pmol/l). CT abdomen /transabdominal ultrasound revealed a 1 cm insulinoma in the uncinate process of the pancreas and the patient later underwent pancreatic enucleation in 2006. Post pancreatic enucleation, 72 h fast was negative. The patient remained asymptomatic post op and re-presented to a locum GP 6 years later with initial symptoms. She was reviewed during her annual follow-up and due to concerns relating to her background she was admitted to the specialist endocrine department for further investigations. A 72 h fast was positive for hypoglycaemia with serum glucose level 1.8 mmol/l, serum insulin 8.6 mIU/l and serum C-peptide 443 pmol/l.