The aim of the study is to investigate the effect of C-peptide administration on nerve function in patients with type 1 diabetes and peripheral sensory neuropathy.

It has been observed that C-peptide administration results in an activation of renal tubular and sciatic endoneural Na/K-ATPase of the rat and stimulation of endothelial nitric oxide synthase. The hypothesis is that C-peptide administration may improve peripheral nerve dysfunction in diabetic neuropathy by increasing nerve blood flow and Na/K-ATPase activity. The purpose of the trial is to investigate the effect of C-peptide administration on diabetic peripheral sensory neuropathy in patients with type 1 diabetes and diabetic neuropathy in the lower extremities.

Inclusion Criteria:

• Subjects who have a duration of type 1 diabetes of more than 5 yrs
• Subjects who are C-peptide deficient
• Subjects who have diabetic distal symmetric neuropathy, according to the criteria defined at the San Antonio Conference on Diabetic Neuropathy 1988
• Subjects who have measurable action potential in the sural nerves
• Subjects who have reduced nerve conduction velocity in the sural nerves

Exclusion Criteria:

• Subjects who have neuropathy or signs of nerve dysfunction which may be a consequence of factors other than type 1 diabetes
• Subjects who have concomitant medication that may interfere with the peripheral nerve function or measurement thereof
• Subjects who are transplanted (islet cell, kidney or pancreas)