I-C-Peptide (C-Peptide) iyi-peptide exhumayo eyakhiwe ngama-amino acid angama-31 enesisindo samangqamuzana esingaba ngu-3021 Daltons. Ama-β-cell we-pancreas ahlanganisa i-proinsulin, okuwuchungechunge lwamaprotheni olude kakhulu. I-Proinsulin ihlukaniswe yaba izingxenye ezintathu ngaphansi kokwenziwa kwama-enzyme, bese izingxenye zangaphambili nangemuva zixhunywa kabusha ukuze zibe i-insulin, eyakhiwe iketango elingu-A no-B, kuyilapho ingxenye ephakathi izimele futhi yaziwa ngokuthi i-C-peptide. . I-insulin ne-C-peptide ikhiqizwa ekugxilweni okulinganayo, futhi ngemva kokungena egazini, i-insulin eningi iyenziwa isebenze esibindini, kuyilapho i-C-peptide ingavamile ukuthathwa yisibindi, kanye nokuwohloka kwe-C-peptide kuhamba kancane kune-insulin. Ukugcwala kwe-C-peptide egazini kuphakeme kune-insulin, imvamisa izikhathi ezingaphezu kwezi-5, ngakho-ke i-C-peptide ikhombisa ngokunembe kakhulu umsebenzi wama-pancreatic islet β-cell. Ukulinganisa izinga le-C-peptide kungasetshenziselwa ukuhlukaniswa kwesifo sikashukela kanye nokuqonda umsebenzi wamaseli e-pancreatic β-cell eziguli ezinesifo sikashukela. Ukulinganisa izinga le-C-peptide kungasetshenziswa ukuhlukanisa isifo sikashukela kanye nokuqonda ukusebenza kwamaseli e-pancreatic β ezigulini ezinesifo sikashukela. Njengamanje, izindlela zokulinganisa i-C-peptide ezisetshenziswa kabanzi emitholampilo yezokwelapha zihlanganisa i-radioimmunoassay, i-enzyme immunoassay, i-electrochemiluminescence, i-chemiluminescence.