The circumferential curvature at the distension pressure of 1.0 (A,B) and 4.0 (C,D) cmH2O in the non-diabetic (A,C) and the diabetic stomach (B,D). The circumferential deformation of the stomach in the non-diabetic rats was significantly bigger than that in the diabetic Goto-Kakizaki (GK) rats, indicating the stiffness of the diabetic gastric wall increased in the diabetic GK rats.