Exenatide is the first synthetic agonist of the GLP-1 (glucagon-like peptide 1) receptor approved for clinical use in patients with type 2 diabetes. The multiplicity of its effects over glucose metabolism, appetite, body weight and its potential capacity to preserve the ?cell mass, makes it an attractive therapeutic alternative. This article attempts to review the current literature on pharmacokinetics, pharmacodynamics, efficacy, and safety of exenatide in humans, derived from the early phase I and II studies, and from the clinical controlled trials that led to its approval for clinical use as a combination therapy with sulphonylureas and metformin.