Genetically engineered insulin, what is this?

Insulin: Years ago, Insulin came from the pancreas of pigs/cows obtained at the slaughterhouse. Now all Insulin is human Insulin which is cloned into bacteria or other simple cells and then purified. Besides being "human", it is much more pure (less contaminants) than the old stuff. Other newer insulins, such as lispro (humalog) have an altered structure to make them more rapid acting.