Insulin used for diabetes was earlier extracted form pancras of slaughtered cattle and pigs insulin consists of two short polypeptide chains , chains , A and chain B that are linked together by disuclphide bridge in mammals including humans insulin is sytheseised as a prohoromoen(loke a pronezyme the pro hormones also need to be precessed before it becomved a fully matrue and functional hormone ) which contains an extra st rech called the c peptide
