Blood sampling. Plasma glucose was determined in capillary samples taken from hyperaemic ear lobes. Venous blood was collected from indwelling venous cannulas placed in a distal forearm vein, for the determination of insulin, C-peptide, glucagon, GLP-1 (total), GLP-1 (intact), glucose-dependent insulinotropic polypeptide (GIP) (total), GIP (intact), and free fatty acids. After drawing basal blood specimens at -15 and 0 min, blood was taken at 15, 30, 45, 60, 90, 120, 180, and 240 min.