|Section2= |Section3= }} C-peptide's a peptide that's made when proinsulin's split into insulin and C-peptide. They split before proinsulin's released from endocytic vesicles within the pancreas -- one C-peptide for each insulin molecule. C-peptide's the abbreviation for "connecting peptide", although its name was probably also inspired by the fact that insulin's also composed of an "A" chain and a "B" chain. C-peptide was discovered in 1967. It shouldn't be confused with c-reactive protein or… (More on C-peptide)