This assay employs the competitive inhibition enzyme immunoassay technique. A monoclonal antibody specific to C-Peptide (CP) has been pre-coated onto a microplate. A competitive inhibition reaction is launched between biotin labeled C-Peptide (CP) and unlabeled C-Peptide (CP) (Standards or samples) with the pre-coated antibody specific to C-Peptide (CP). After incubation the unbound conjugate is washed off. Next, avidin conjugated to Horseradish Peroxidase (HRP) is added to each microplate well