Gastric Inhibitory PolypeptideGastrointestinal HormonesReceptors, Gastrointestinal HormoneGlucagon-Like PeptidesGlucagon-Like Peptide 1XylitolSecretinGlucagonMotilinInsulinBlood GlucosePeptide PHICholecystokininGastrinsDuodenumGlucoseDietary CarbohydratesProtein PrecursorsAdministration, OralDiabetes Mellitus, Type 2Peptide FragmentsIslets of LangerhansDogs