Non-insulin injectable treatments (glucagon-like peptide-1 and its analogs) and cardiovascular disease

Glucagon-like peptide-1 (GLP-1) [GLP-1 (7-36)-amide] plays a fundamental role in regulating postprandial nutrient metabolism. GLP-1 acts through a G-protein-coupled receptor present on the membranes of many tissues, including myocardium and endothelium. GLP-1 is cleaved by the dipeptidyl peptidase-4 enzyme to its metabolite GLP-1 (9-36)-amide within 1-2 min of its release into the circulation. Investigations have been done in humans and in animal models to determine whether GLP-1 has effects on the myocardium. Infusions of GLP-1 increase cardiac function in ischemic and non-ischemic cardiovascular disease. In humans and animal models, constant infusions of GLP-1 decrease the size of infarction and improve myocardial function in ischemic/reperfusion injury. In cardiomyopathy and heart failure, infusions of GLP-1 improve myocardial function. These beneficial effects of GLP-1 on cardiac function are mediated by both GLP-1 receptor activation and GLP-1 receptor independent actions. Infusions of the metabolite GLP-1 (9-36)-amide improve cardiac function in experimental animals with cardiovascular disease even though the metabolite does not bind to the GLP-1 receptor. The beneficial effects of GLP-1 on the heart occur in the presence of a GLP-1 receptor antagonist and in animals devoid of GLP-1 receptors. Preliminary data in animals with available GLP-1 receptor agonists and cardiac disease suggest that exenatide has beneficial effects in porcine models of ischemic heart disease. The animal data with liraglutide are inconclusive. Clinical trials with exenatide and liraglutide show significant improvements in weight, systolic blood pressure, lipid profiles, and other cardiovascular risk factors. Whether these will decrease cardiovascular events is currently under investigation.