[Measurement of proinsulin, insulin and C-peptide in human blood by high performance liquid chromatography]

The technique of measuring insulin, proinsulin, and C-peptide in human blood by high-pressure liquid chromatography is described. Donors, subjects with abnormal glucose tolerance, and patients with type I diabetes were examined. The main advantage of the method over radioimmunoassay and enzyme immunoassay is the possibility of simultaneous differentiated measurement of human insulin and animal hormone administered parenterally, and separation of insulin and its precursor on the basis of difference in molecular weight and charge of molecules. The results indicate that patients with type I diabetes retain the secretion of endogenous insulin, although its level is appreciably lower than in healthy donors, and the structure of its molecules is heterogeneous, which is proven by a biphasic chromatographic peak. Inhibition of proinsulin transformation into insulin is one probable mechanism of impairment of glucose tolerance. High-pressure liquid chromatography can be used at clinical laboratories for examinations of diabetics.