The blood glucose concentration is e.g. monitored by glucose-sensing cells in the portal vein area and in different regions of the brain, resulting in parasympathetic stimulation of insulin release in hyperglycaemia and glucagon release in hypoglycaemia, as well as sympathetic inhibition of insulin and stimulation of glucagon secretion in hypoglycaemia (22,23). The gene discussed is GCG; the disease is Hypoglycemia.