A composition for the treatment of impaired glucose tolerance (IGT) including a compound which binds to a receptor for glucagon-like peptide-1, and a pharmaceutical carrier. The amount of the compound present is an effective amount to improve pancreatic .beta.-cell sensitivity to blood glucose levels in a human with IGT. Also, a method for improving the pattern of insulin secretory responses in a human with IGT by administering to the human a composition comprising a compound which binds to a receptor for glucagon-like peptide-1 and a pharmaceutical carrier.