Re: Pandora's box?
Think it was sheep originally,
I believe the original insulin extracts were done from horses. Pigs, cows and even fish have been used too. Each of them is similar, but not identical to human insulin and each has their own set of problems.
Nowadays, a lot of it is made by recombitant DNA tweaking of bacteria (including the human insulin-producing gene in a bacteria genome so that one of the waste products that it produces is insulin). First done in the early 80s.