■ Abstract BACKGROUND:Gastrointestinal complications in diabetes may affect glucose and endocrine homeostasis. Glucosedependent insulinotropic peptide (GIP), glucagon-like peptide-1 (GLP-1), and leptin regulate glucose homeostasis, food intake, and gastric emptying. AIM: The aim was to investigate associations between diabetes complications and glucose homeostasis and plasma levels of GIP, GLP-1, and leptin. METHODS: Sixteen diabetes patients (seven men) were examined with gastric emptying scintigraphy and 72-h continuous subcutaneous glucose monitoring, 14 with the deep-breathing test, and 12 with esophageal manometry. A fiber-rich breakfast was given during the second day of glucose registration. Blood samples were taken 10 min and right before a fat-rich breakfast, as well as 10, 20, 30, 45, 60, 90, 120, 150, and