The effect of acute hypercalcaemia on arginine induced growth hormone release in diabetic man

The effect of mild hypercalcaemia on the growth hormone (GH), C-peptide and glucose responses to arginine infusion in patients with insulin-dependent idiopathic diabetes mellitus (ID) was compared with that observed in patients whose diabetes was secondary to idiopathic haemochromatosis (IH) and chronic pancreatitis (CP). The summated GH responses to arginine infusion alone were similar in all three groups. Mild hypercalcaemia significantly diminished the GH response to arginine in patients with secondary diabetes, but not in those with ID. As the blood glucose and C-peptide responses were similar in the presence of a normal or raised serum calcium, the differences in GH response could not be ascribed to changes in blood glucose levels or to alterations in endogenous insulin release. For reasons as yet unknown, hypercalcaemia appears to have more of a stabilizing effect on the pituitary somatotrophic granules of those with secondary diabetes than in those with ID.