What are GLP-1 receptor agonists and what makes them unique?

Glucagon-like peptide-1 receptor agonists, or GLP-1 agonists, including semaglutide, liraglutide, and dulaglutide, mimic the incretin hormone GLP-1. They stimulate insulin secretion only when blood glucose is elevated, suppress glucagon, slow gastric emptying, and promote satiety, leading to significant weight loss in addition to glucose lowering. They reduce hemoglobin A1C by 1 to 1.8 percent. Major cardiovascular and renal benefits have been demonstrated in clinical trials. Common side effects are nausea, vomiting, and diarrhea.