Results of those techniques established a reproducible proteomic signature of DN progression, with C3-, C4- and C5-derived peptide enrichment, particularly C3a, C3dg, C5a, and sC5b-9, in DN patients compared with diabetic controls without nephropathy [71,72,73,74], as detailed further in the urinary proteomics section. This evidence concerns the gene C5AR1 and kidney disorder.