A tumour that secretes glucagon-like peptide-1 and somatostatin in a patient with reactive hypoglycaemia and diabetes.

Glucagon-like peptide 1 (GLP-1), an insulinotropic hormone normally synthesised in the intestinal mucosa and released in response to a meal, is essential for normal glucose homoeostasis. There is much interest in the use of GLP-1 to treat diabetes, since the risk of hypoglycaemia is thought to be low. We report an instance of a 45-year-old woman with a GLP-1 and somatostatin secreting neuroendocrine tumour who presented with reactive hypoglycaemia and hyperglycaemia, but who was subsequently cured by surgery. This case, of a neuroendocrine tumour secreting GLP-1 and causing reactive hypoglycaemia, indicates a potential adverse effect of GLP-1 therapy for diabetes.