Evolution of glucagon-like peptide-1 receptor agonists for the treatment of type 2 diabetes

Glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1RAs) are a class of antidiabetic drugs developed over the past 15 years. GLP-1, a gastrointestinal peptide hormone that contributes to the postprandial “incretin effect”, stimulates glucose-dependent insulin secretion. The incretin effect is greatly diminished in type 2 diabetes, but can be restored by GLP-1RAs. These drugs also exert other GLP-1 effects, including reducing glucagon secretion, delaying gastric emptying, reducing food intake, improving cardiac ventricular function, and lowering blood pressure. Short-acting GLP-1RAs are administered once daily (lixisenatide) or twice daily (exenatide); long-acting GLP 1RAs are administered once daily (liraglutide) or once weekly (slow-release exenatide, dulaglutide, albiglutide). All GLP-1RAs significantly reduce glycated hemoglobin (HbA1c) in patients with type 2 diabetes whose glycemic control is inadequate with oral antidiabetic drugs. Compared with other antidiabetic medications, GLP-1RAs provide better glycemic control with the additional benefit of weight loss. Within this class, long-acting GLP-1RAs are more efficacious than short-acting GLP-1RAs, with similar or lower risk of hypoglycemia and lower incidence of gastrointestinal adverse effects. Head-to-head trials and a network meta-analysis suggest that once daily liraglutide is the most effective GLP-1RA in reducing HbA1c. Dulaglutide is the only once-weekly GLP 1RA demonstrated to be noninferior to liraglutide. The once-weekly GLP-1RAs offer additional advantages to patients, including fewer injections and easy-to-use, single-dose pen devices. Despite the relatively recent development of GLP-1RAs, international diabetes guidelines recognize the benefits of this class of drugs and recommend them as a treatment option for patients with type 2 diabetes.