GLP1R and diabetes mellitus: A similar dose of linagliptin (1 mg/kg po) to that used in this study (2 mg/kg po) has been demonstrated to effectively inhibit DPP-4 activity and to increase GLP-1 in Zucker diabetic fatty rats [24] but in this type 1 model of diabetes, where the beta pancreatic cells are destroyed by necrosis, it is not possible to elevate insulin secretion to decrease glucose.