Endocrine Abstracts

Non-islet cell tumour hypoglycaemia (NICTH) is a rare paraneoplastic condition associated with epithelial or mesenchymal tumours. We report a case of NICTH in a man with poorly controlled diabetes who was initially thought to have diabetes remission. A 50-year-old man with a 4-year history of diabetes (HbA1c 12% at diagnosis) reported improvement in diabetes control within a year (HbA1c 5%) with oral glucose-lowering agents (OGLA). His OGLA were subsequently stopped, and he was labelled by primary care as achieving diabetes remission, maintaining a HbA1c of <6% without treatment or lifestyle modifications. He was referred to Endocrinology after developing new-onset episodic blurred vision and tremors on fasting, associated with 5-kg weight gain over 6-months. Symptoms resolved with meals. Capillary blood glucose was reported to be <3mmol/L during these episodes. Clinical examination noted a hard suprapubic mass. In view of unexplained hypoglycaemia, a 72-hour supervised fast was performed and precipitated hypoglycaemia at 7-hours (plasma glucose 2.6mmol/l) with serum ketone <0.6mmol/l, C-peptide 31 pmol/l (260-1729 pmol/l) and insulin <1.6mU/L (2.6-24.9mU/l). Plasma glucose increased from 2.6mmol/L to 4.7mmol/L with IV glucagon 1 mg at fast termination, suspicious for insulin-like growth factor-2 (IGF2) excess. Computed tomography of the abdomen confirmed a 15.5x11.5x13.4 cm lobulated soft-tissue mass in the lower abdomen. Serum IGF1 and IGF2 were 34µg/L (IGF1 79-205µg/l) and 1154ng/ml (IGF2 333-967ng/mL) respectively. IGF2:IGF1 ratio was 33 (normal value <3.0), confirming IGF2 excess. He was started on prednisolone and advised on frequent meals containing complex carbohydrates. He subsequently underwent complete open resection of his pelvic tumour. Histology revealed a solitary fibrous tumour with immunohistochemical staining of patchy STAT-6 expression. Hypoglycaemic episodes resolved post-operatively and repeat IGF2 measurement is pending. NICTH can mimic spontaneous remission of diabetes and progress to symptomatic hypoglycaemia. Clinicians should maintain a high index of suspicion for paraneoplastic phenomenon in patients with diabetes reporting unexplained hypoglycaemia.