C-Peptide as a Remedy for Diabetic Microangiopathy?

Abstract

Insulin, connecting peptide (C-peptide) is part of the proinsulin molecule from which it is cleaved by a serine protease within the pancreatic β-cells and subsequently released in equimolar amounts with insulin (1–3). Primarily, C-peptide, which is predominantly cleared by the kidney, was regarded a biologically inert byproduct of insulin secretion and an unneeded contaminant of commercial insulin preparations (1,4), neither affecting glucose metabolism nor lipolysis (5). In contrast, radioimmunological determination of C-peptide turned out to be a useful tool for diagnostic purposes in diabetes research at large, including the estimation of insulin production rates in healthy humans (6) and of residual insulin release in type 1 diabetic patients (7) as well as in vitro (8). From 1995 onwards the question of C-peptide’s biological activity was raised again, and it was assigned a multitude of physiological actions affecting renal, neural, and circulatory functions as well as a wide spectrum of signaling phenomena in vitro (9,10). These reviews raised the hope that C-peptide might find a role in treatment of diabetes-associated late complications, particularly diabetic microangiopathy. Any such proof would be of great clinical importance as the global …