It's unclear to me if the lack of competition is due to IP laws. For all I know, they've been coasting with the same production methods for 20+ years (the article mentions that insulin was relatively cheap in 2002). With such large profit margins there wouldn't be much incentive to improve anything.
I don't know the exact details and I could be wrong, but my understanding is:
There is IP around the production process (specifically the genetic strain of e-coli). Because the production process is biological, generics produced with a different process are not automatically approved by the FDA and have to undergo an expensive approval process. Thus the goal here is to devolop a process with open IP and get that process approved.
