This study aimed to compare jejunal contractile responses to muscarinic receptor stimulation between obese patients with type 2 diabetes (OB+/DM+) and obese patients without diabetes (OB+/DM−), and to assess the effects of GLP-1 and GIP on jejunal contraction in relation to jejunal muscle expression of these peptides, their receptors, and DPP-4. The gene discussed is GCG; the disease is type 2 diabetes mellitus.