Liraglutide, a once-daily human glucagon-like peptide-1 (GLP-1) analog, was approved by the US Food and Drug Administration in 2010 for the treatment of type 2 diabetes mellitus (T2DM). Glucagon-like peptide-1 enhances insulin secretion and inhibits glucagon in a glucose-dependent manner. The efficacy and safety of liraglutide were evaluated in 6 phase 3 trials in > 4000 patients in the Liraglutide Effect and Action in Diabetes (LEAD) program, in another trial in comparison with sitagliptin, and in another trial where basal insulin was added to liraglutide + metformin. At liraglutide doses of 1.2 mg or 1.8 mg once daily, significant mean reductions in glycated hemoglobin (HbA1c) (1%-1.6%) and fasting plasma glucose (15-43 mg/dL), as well as sustained weight loss (2-3 kg) and a low rate of hypoglycemia occurred. Mild and transient nausea, reported in 6% to 41% of patients, was the most frequent adverse event reported. Incretin-based therapies such as liraglutide provide an important expansion of options for the treatment of T2DM.