One bit of nuance here is that you cannot buy FDA approved non-human insulin in the U.S. That’s not because of an action by the FDA, but just that the manufact

One bit of nuance here is that you cannot buy FDA approved non-human insulin in the U.S. That’s not because of an action by the FDA, but just that the manufacturers stopped selling it between 1998 and 2006: https://www.fda.gov/drugs/frequently-asked-questions-popular-topics/questions-and-answers-importing-beef-or-pork-insulin-personal-use#Q-1 https://www.fda.gov/drugs/frequently-asked-questions-popular... So your only option is to buy the modern day synthetic analogs - or illegally import the old stuff, which the FDA notes here it has the right to block, but may allow under exceptional circumstances.