Basal and insulin stimulated substrate metabolism in tumour induced hypoglycaemia; evidence for increased muscle glucose uptake.

While it has very recently been reported that tumour induced hypoglycaemia is characterised by elevated production of insulin-like growth factor 2, the tissues responsible for induction of hypoglycaemia are largely unknown. We have investigated a patient with a large retroperitoneal mass and spontaneous hypoglycaemia. When compared to a reference population the patient displayed: (1) An increased glucose disposal rate and a five-fold elevation of forearm glucose uptake. (2) A decreased endogenous glucose production rate. (3) Decreased circulating levels of lipid intermediates. (4) Increased glucose oxidation and decreased lipid oxidation. (5) Low circulating levels of insulin-like growth factor 2 and insulin-like growth factor-binding protein-3 and normal levels of insulin-like growth factor 1. (6) Normal insulin sensitivity (euglycaemic glucose clamp). Blood concentrations of insulin, C-peptide, proinsulin, glucagon, growth hormone and catecholamines were within normal range, but the growth hormone response to hypoglycaemia was blunted. The data suggest that the mechanisms behind tumour induced hypoglycaemia are of systemic nature and that the tissue most prominently affected is striated muscle.