I think the Amish and the folks like them are fairly well prepared, except for those on critical medicines since in most cases the government will not allow you to stockpile. Heaven help folks with serious diabetes or heart conditions, etc. My guess though is that there will be small pockets that survive quite well. The Amish in Smyrna Maine seem largely self sufficient as one example.
insulin? My wife buys her’s in a 5 pack of pen injectors. They last almost 1 month per pen. So her perscription is for 4-5 months. Now that is not forever, but it is quite a while.
Until the pen is opened, it has shelf life. Once it is opened it is good for 30 days. She uses one up in just under the 30 days, so no waste.
She only recently started taking shots, before it was pills. She could probably survive without the shots, by seriously restricting her sugar intake and her diet.