Earlier the insulin was obtained from the pancreas of slaughtered cows and pigs. The process was tedious, time consuming, difficult and the yield of insulin would be low. The animal insulin differed in structure with the human insulin by few amino acid sequences which resulted in the animal insulin being recognized as a foreign body inside the human body which resulted in allergies and other side effects.
The advantages of recombinant insulin over traditional insulin are:
It is less expensive
It causes fewer allergic reactions
It is more rapidly absorbed and shows its effectiveness over shorter period of time