[The occurrence of proinsulin and C-peptide in healthy humans and in diabetics].

Chemistry, biochemistry and physiology of proinsulin and C-peptide are summarized. A short characterization of the radioimmunological methods for measuring C-peptide and proinsulin follows. The determination of C-peptide and proinsulin which was mainly carried out in serum or plasma essentially improved our knowledge about the function of the beta-cells in the islets of Langerhans in healthy subjects and diabetic patients. The paper reports on the occurrence and the course of C-peptide and proinsulin in healthy subjects and in diabetics of type I and II.