The endocrine function of the pancreas consists of the promotion of storage of nutritive substances after meals through the liberation of insulin and to guarantee the mobilization of this food energy through the secretion of glucagon during fasting. Increased hormone production may result from tumors of the islet cells (insulin: insulinoma; glucagon: glucagonoma; gastrin: Zollinger-Ellison syndrome). An absolute or relative insulin deficiency is a characteristic of diabetes mellitus, in which a relative hyperglucagonemia is also of possible pathophysiological significance. This increased secretion of glucagon can be suppressed by somatostatin. While the clinical application of somatostatin in diabetes mellitus seems problematic at present, the use of a glucose-controlled system of insulin infusion ("artificial pancreas") makes possible a metabolic state approaching the healthy condition.