Are all GLP-1 agonists equal in the treatment of type 2 diabetes?

GLP-1, a peptide hormone secreted from the gut, stimulating insulin and suppressing glucagon secretion was identified as a parent compound for novel treatments of diabetes, but was degraded (dipeptidyl peptidase-4) and eliminated (mainly by kidneys) too fast (half-life 1-2 min) to be useful as a therapeutic agent. GLP-1 receptor agonist has been used to treat patients with type 2 diabetes since 2007, when exenatide (twice daily) was approved in 2007. Compounds with longer duration of action (once daily, once weekly) and with increasingly better efficacy with respect to glycaemic control and body weight reduction have been developed, and in a recent ADA/EASD consensus statement, were recommended as the first injectable diabetes therapy after failure of oral glucose-lowering medications. Most GLP-1 receptor agonists (lixisenatide q.d., liraglutide q.d., exenatide q.w., dulaglutide q.w., albiglutide q.w., semaglutide q.w., all for s.c. injection, and the first oral preparation, oral semaglutide) have been examined in cardiovascular outcomes studies. Beyond proving their safety in vulnerable patients, most of whom had pre-existing heart disease, liraglutide, semaglutide, albiglutide, and dulaglutide reduced the time to first major adverse cardiovascular events (non-fatal myocardial infarction and stroke, cardiovascular death). Liraglutide, in addition, reduced cardiovascular and all-cause mortality. It is the purpose of the present review to describe clinically important differences, regarding pharmacokinetic behaviour, glucose-lowering potency, effectiveness of reducing body weight and controlling other cardiovascular risk factors, and of the influence of GLP-1 receptor agonist treatment on cardiovascular outcomes in patients either presenting with or without pre-existing cardiovascular disease (atherosclerotic, ischemic or congestive heart failure).