Clinical significance of circulating C-peptide in diabetes mellitus and hypoglycemic disorders
A. H. Rubenstein, H. Kuzuya and D. L. Horwitz
Proinsulin is converted to insulin and C-peptide in the pancreatic in the
pancreatic beta cells: the latter two peptides are secreted in equimolar
concentrations. Thus, measurements of serum C-peptide provide a means of
assessing pancreatic beta cell function in addition to that of insulin.
This technique has proved particularly useful in insulin treated diabetic
patients in whom the development of circulating insulin antibodies
interferes with the radioimmunoassay of the hormone. The C-peptide assay
has also been used to facilitate the diagnosis of various hypoglycemic
conditions, including islet cell tumors and factitious injection of
insulin. The extraction of C-peptide in the urine reflects average serum
values over a period of time and urine C-peptide measurements are
especially useful in children or individuals in whom repeated blood
sampling is difficult.
