C-Peptide (C-Peptide) wani peptide ne mai haɗawa wanda ya ƙunshi amino acid 31 tare da nauyin kwayoyin halitta na kimanin Daltons 3021. Kwayoyin β na pancreas suna haɗa proinsulin, wanda shine dogon sarkar furotin. Ana raba Proinsulin zuwa sassa uku a ƙarƙashin aikin enzymes, kuma an sake haɗa sassan gaba da baya don su zama insulin, wanda ya ƙunshi sarkar A da B, yayin da ɓangaren tsakiya yana da zaman kansa kuma an san shi da C-peptide. Ana fitar da insulin da C-peptide a cikin yawan daidai gwargwado, kuma bayan shiga jini, yawancin insulin yana lalacewa ta hanyar hanta, yayin da ba kasafai ake ɗaukar C-peptide ta hanta ba, ƙari da lalacewar C-peptide yana da jinkiri fiye da insulin, don haka yawan C-peptide a cikin jini ya fi na insulin girma, yawanci fiye da sau 5, don haka C-peptide yana nuna aikin ƙwayoyin β-cell na pancreas daidai. Ana iya amfani da ma'aunin matakin C-peptide don rarraba ciwon suga da kuma fahimtar aikin ƙwayoyin β-cell na pancreas na marasa lafiya da ciwon suga. Ana iya amfani da ma'aunin matakin C-peptide don rarraba ciwon suga da kuma fahimtar aikin ƙwayoyin β-cell na pancreas a cikin marasa lafiya da ke fama da ciwon suga. A halin yanzu, hanyoyin auna C-peptide da ake amfani da su sosai a asibitocin likitanci sun haɗa da radioimmunoassay, enzyme immunoassay, electrochemiluminescence, da chemiluminescence.