C-peptide revisited--new physiological effects and therapeutic implications.

Recent studies have demonstrated that replacement of C-peptide to normal physiological concentrations in insulin-dependent diabetic (IDDM) patients on a short-term basis (1-3 h) results in decreased glomerular hyperfiltration, augmented glucose utilization and improved autonomic nervous function. More prolonged administration (1-3 months) of C-peptide to IDDM patients is accompanied by improvements in both renal and autonomic nervous function. Moreover, both in-vitro and in-vivo studies indicate that C-peptide may have a role in the regulation of insulin secretion. The effects of C-peptide may in part be explained by its ability to stimulate Na+,K(+)-ATPase activity. In conclusion, the combined findings indicate that C-peptide is a biologically active hormone. The possibility that C-peptide therapy in IDDM patients may be beneficial should be considered.