By using the above monoclonal antibodies, it is possible to measure intact exendin-4 by a sandwich ELISA which is not subject to interference from GLP-1 or other glucagon-related peptides that may be present. ABS 033-10 is used as capture antibody in combination with a biotinylated detection antibody from the ABS 012 series. The best sensitivity in an unoptimized buffer assay was obtained with biotinylated ABS 012-35 as the detection antibody.