Severe recurrent hypoglycaemia in a patient with aggressive melanoma

We present a case of hypoglycemia in a young patient without diabetes mellitus who presented initially with enlarging neck mass and weight loss, and was found to have aggressive melanoma with metastasis to multiple organs and diffuse lymphadenopathy. He had presented to the emergency room two times with neuroglycopenic symptoms that required admission and intravenous dextrose continuously. Evaluation of hypoglycemia included C-peptide, insulin levels, insulin-like growth factor (IGF) -I and -II, and ß- hydroxybutyrate. Insulin levels were suppressed appropriately during hypoglycemia, however, IGF-II:IGF-I ratio was high, suggesting non-islet tumour induced hypoglycemia. The presence of IGF-II produced by large tumors results in a low hepatic glucose output and increased uptake by skeletal muscle, resulting in hypoglycemia especially in a patient with extremely low appetite such as our patient. Treating the culprit malignancy leads to resolution of hypoglycemia, but corticosteroids have been used to suppress IGF-II levels and alleviate symptoms.