5 mL (1 mL min.) aliquot of 24 hour Urine. Do not use preservatives. Record 24 hour urine volume on container and test request form. Ship frozen.
C-Peptide is useful in distinguishing Insulinomas from exogenous insulin administration. Its concentrations are severely decreased or absent in Type I Diabetes mellitus. C-Peptide is also useful in monitoring patients who have received islet cell or pancreatic transplants.