Or indeed any insulin?
I know the starting point these days is genetically modified yeast or bacteria (or algae?) which creates a lot of the insulin protein, rather like yeast creates alcohol in beer.
So I'm assuming they start with a vat of nutritious soup, put the starter yeast or whatever in, watch it grow for a while, just as you do for beer and wine, then take it out and process it. (I'm guessing it's done in batches - continuous might have too high a chance of something going wrong).
Processing is where it starts to get vague for me - you've got to extract the insulin from the soup. How is that done these days? Some form of chromoatography? Or something which binds to insulin and can then release it? Or something else?
Once we've got some insulin-only soup, how do we then get u100? Do they simply measure how much is in there and dilute as appropriate?
(Despite the language I've just used, I'm reasonably scientifically literate, so please don't hold back on explanations if you have one - I can understand most chemical and engineering things
)