IncretinsGastric Inhibitory PolypeptideGlucagon-Like Peptide 1Dipeptidyl-Peptidase IV InhibitorsDipeptidyl Peptidase 4Glucagon-Like PeptidesReceptors, GlucagonGastric BypassDiabetes Mellitus, Type 2GlucagonBariatric SurgeryObesity, MorbidInsulinInsulin-Secreting CellsBlood GlucoseHypoglycemic AgentsPostprandial PeriodGlucoseGlucose Tolerance Test