Endothelial and Metabolic Effects of Glucagon-like Peptide-1 (GLP-1) in Coronary Circulation in Patients With Type 2 Diabetes Mellitus

GLP-1 is an incretin hormone which is discharged from the intestines after food intake. The hormone is known for its powerful insulinotropic and trophic effects on the beta cells in the pancreas and is currently used as an anti-diabetic agent in patients with type 2 diabetes (T2DM). GLP-1 receptors are widely distributed including on the endothelial cells in both coronary and skeletal muscle circulation and on the myocardium. GLP-1-receptor studies on knock-out mice have shown that they exhibit a reduced myocardial contractility and reduced diastolic heart function. GLP-1 also shows beneficial cardiovascular effects in patients with acute myocardial infarctions and dogs with dilated cardiomyopathy in that the left ventricle function and endothelial dysfunction improves after GLP-1 treatment via insulin-independent mechanisms. Preclinical studies indicate that exogenous administrated GLP-1 in physiological concentrations can improve perfusion but this has never been tested in humans. It is also unknown whether GLP-1 can directly increase the glucose/metabolite uptake across both cardiac and skeletal muscle in an insulin independent manner. Unpublished studies do however indicate that the improvement in the cardiovascular system is largely dependent upon a high blood glucose level and only partially dependent upon the antiglycemic effects of GLP-1. In the proposed studies the investigators wish to examine the physiological role of GLP-1 receptor stimulation both with regard to perfusion, metabolic improvement as well as cardiac inotropic. These studies will be conducted in both healthy and in T2DM patients.