Background: Glucagon-like peptide-1 (GLP-1) possesses insulinotropic and glucagonostatic properties, and, therefore, GLP-based antidiabetic therapies have been developed. Even though the insulinotropic potency of GLP-1 has been shown to be reduced in patients with type 2 diabetes mellitus (T2DM), a small dose of GLP-1 is capable of normalizing the beta-cell responsiveness to glucose in these patients. The glucagonostatic potency of GLP-1 in patients with T2DM is not known, and, furthermore, the capability of GLP-1 to reestablish normal glucagon secretion in these patients remains to be elucidated.