Tumour-induced hypoglycaemia due to 'big' IGF-II

A 57-year-old woman with a slowly growing intraabdominal leiomyosarcoma developed life-threatening hypoglycaemia. Plasma C-peptide levels were low (0.08 nmol L-1 and < 0.05 nmol L-1, reference interval 0.18-0.63 nmol L-1). Total IGF-II was normal (760 ng mL-1) whilst 'big' IGF-II was markedly elevated (440 ng mL-1). After surgical tumour reduction, 'big' IGF-II levels in plasma normalized (117 ng mL-1) and the patient experienced no new episodes of hypoglycaemia. Life-threatening hypoglycaemia due to tumour production of IGF-II can be ameliorated by reduction of the tumour burden and should be kept in mind even in incurable patients.