Environmental and lifestyle factors together account for the dramatic increase of type 2 diabetes in the past decades, in which defective insulin secretion emerges as the major culprit. Glucagon-like peptide l (GLP-1) is a peptide secreted from the intestine in response to nutrient ingestion, and plays an essential role in the regulation of blood glucose level by stimulating glucoses-dependent insulin secretion. Recently, GLP-1 develops to be a viable therapeutic target for the treatment of type 2 diabetes, by means of GLP-1 receptor agonists and dipeptidyl peptidase-4 inhibitors. Stemmed fi^om its potent physiological activities, GLP-1-based therapies are clinically efficient and safe for both early and late stages of the disease, with low risk of adverse events. In this review, a comprehensive understanding of GLP-1 biology and the recent development of GLP-1-based antidiabetic therapy are summarized.