Abstract
Recent results indicate that proinsulin C-peptide, contrary
to previous views, exerts important physiological effects and
shows the characteristics of a bioactive peptide. Studies in
type 1 diabetes, involving animal models as well as patients,
demonstrate that C-peptide in replacement doses has the
ability to improve peripheral nerve function and prevent or
reverse the development of nerve structural abnormalities.
Peripheral nerve function, as evaluated by determination of
sensory nerve conduction velocity and quantitative sensory
testing, is improved by C-peptide replacement in diabetes type
1 patients with early stage neuropathy. Similarly, autonomic
nerve dysfunction is ameliorated following administration of C
peptide for up to 3 months. As evaluated in animal models of
type 1 diabetes, the improved nerve function is accompanied by
reversal or prevention of nerve structural changes, and the
mechanisms of action are related to the ability of C-peptide
to correct diabetes-induced reductions in endoneurial blood
flow and in Na+,K+-ATPase activity and modulation of neurotrophic
factors. Combining the results demonstrates that C-peptide may be
a possible new treatment of neuropathy in type 1 diabetes.