Gary Adams, Susannah Champion, Gemma Figg and Alex Jervis
Proinsulin C-peptide is biologically active and exerts a protective physiological role in Type 1 Diabetes mellitus. We evaluated the effect of C-peptide replacement on the renal and nerve function of patients with T1DM and attempted to determine the mechanism by which it may exert its effects. An electronic search for randomised control trials was carried out in the following databases; Pubmed, EMBASE, Medline, CINAHL, CENTRAL and Proquest. The primary results from included trials were statistically combined in a meta-analysis. Six (6) randomised control trials met the inclusion criteria. Two (2) investigated the effects of C-peptide on kidney function. Three (3) investigated the effects of C-peptide on nerve function. One (1) randomised control trial investigated the effect of C-peptide on both kidney and nerve function. C-peptide was found to exert statistically significant beneficial effects upon urinary albumin excretion, glomerular filtration rate and autonomic and sensory nerve function. When the results from these trials were combined in a meta-analysis, C-peptide was found to exert statistically significant beneficial effects upon albumin excretion and autonomic nerve function when compared to placebo. There is increasing evidence that C-peptide ameliorates the type 1 diabetes associated microvascular dysfunction seen in the kidneys and nerves. The mechanism of Cpeptides action appears to be complex and multifaceted and is not fully understood. Evidence from cell systems and experimental models of diabetes suggests that Cpeptide may influence Na+K+-ATPase and endothelial nitric oxide synthase activity in order to exert its beneficial effects.