Endocrine Abstracts

Malignant insulinoma is a rare pancreatic neuroendocrine tumour. Challenges with management 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 1.8mmol/l associated with neuroglycopaenia. Subsequent biochemistry revealed inappropriately normal C-peptide 2.64 mg/l (0.80-5.20), insulin 13.81 mIU/l (3.40-19.60) and elevated pro-insulin 138pmol/l (3.4-20.4) with paired fasting serum glucose 2.8mmol/l confirming insulin-dependent hypoglycaemia. Imaging showed a poorly defined heterogenous mass at the pancreatic body and tail. Endoscopic ultrasound with sampling from fine needle aspiration confirmed a pancreatic neuroendocrine neoplasm with poorly-differentiated features, staining positively for SSTR2A, chromogranin, and synaptophysin. He was treated with first line temozolamide/capecitabine neoadjuvant chemotherapy, followed by temozolamide monotherapy. After a therapeutic trial of short acting somatostatin analogue (Octreotide), he was commenced on Lantreotide for hypoglycaemia. Continuous glucose monitoring (CGM) was used to monitor hypoglycaemia and assess response to treatment. Time below range (TBR) prior to chemotherapy was up to 7%. Management of symptomatic fasting hypoglycaemia included clinical nutrition input, diazoxide, and glucocorticoids, which were later reduced due to hyperglycaemia. He underwent subsequent extensive surgical resection with histology showing grade 3 NET, Ki67 up to 40%, ENETS stage pT4N2, R0. Due to radiological recurrence of disease and worsening hypoglycaemia, TBR 18%, nocturnal cornstarch was introduced in combination with high protein snacks nocte resulting in temporary normalisation of fasting blood glucose. He was commenced on everolimus and lutetium peptide receptor radionucleotide therapy (PRRT), without further episodes of hypoglycaemia to date, TBR 0%. The management of hypoglycaemia in malignant insulinoma can be challenging. The use of CGM devices has improved the ability to establish patterns for targeted treatments. The use of cornstarch as a non-pharmacological option for treatment of refractory hypoglycaemia in malignant insulinoma was successful as a bridge to further pharmacological treatments in this case.