Endocrine Abstracts

Malignant insulinoma is a rare pancreatic neuroendocrine tumour. Challenges include the clinical implications and management of refractory hypoglycaemia. A 42-year-old gentleman presented with behavioural changes secondary to point-of-care-confirmed hypoglycaemia of 1.8 mmol/l, associated with neuroglycopaenia. Biochemistry during fasting hypoglycaemia revealed an elevated C-peptide, with Whipple’s triad fulfilled. Imaging showed a heterogeneous mass in the pancreatic body and tail. Endoscopic ultrasound with limited sampling confirmed a pancreatic neuroendocrine neoplasm with poorly differentiated features, consistent with a malignant insulinoma. He was treated with first-line temozolomide/capecitabine neoadjuvant chemotherapy and somatostatin analogue lanreotide for hypoglycaemia. Continuous glucose monitoring (CGM) was used to assess hypoglycaemia and assess response to treatment, with a pre-treatment time below range (TBR) of 7%. Management of symptomatic fasting hypoglycaemia included clinical nutrition input, diazoxide, and glucocorticoids, which were later tapered due to hyperglycaemia. He underwent extensive surgical resection, with a transient normalisation in TBR. Histology showed a grade 3 neuroendocrine tumour NET, Ki-67 index 40%, ENETS stage pT4N2, R0 resection. However, due to radiological recurrence of disease and worsening hypoglycaemia (TBR 18%), nocturnal cornstarch and high-protein snacks were introduced, temporarily reducing TBR. He was subsequently commenced on everolimus and lutetium peptide receptor radionuclide therapy (PRRT), with no further episodes of hypoglycaemia to date (TBR 0%). The management of malignant insulinoma is enhanced by the use of CGM devices in establishing patterns of hypoglycaemia for targeted treatments. In this case, cornstarch was a successful non-pharmacological bridge to second-line pharmacological therapy in the treatment of refractory hypoglycaemia.