Until recently, C-peptide was seen as an inert molecule that contributed solely tothe biosynthesis of insulin,3 aiding in thecorrect folding of insulin and the formation of disulfide bridges.1 Multiple functional roles have been recentlydescribed for C-peptide, including binding to cell membranes, activation ofsignaling pathways, physiological effects, and protection against complicationsderived from diabetes mellitus (DM).3 Preclinical trials showed that C-peptide may improve the outcomesrelated to diabetic kidney disease (DKD).4,5. The gene discussed is INS; the disease is diabetic kidney disease.