I have had this problem myself.  THis is where the insurance company gets tight...

I also get around this by ordering my meds as soon as possible via mail order for the 90 day supply.  I also have an rx on file at a local pharmacy.  I have never had a problem, but this is a fear of mine.  I have discussed it with my endo, he tries to make the rx over the amount - but then there is the leagal aspect of writing an rx for more than what is required (know what I mean, sort of insurance fraud?).  This is something I believe I need to bring up with the insurance board for our insurance company.  I have not done this because I have not had a problem in the 9+ years of dealing with CAH.  We have come close, but have never used up all cortef on hand.  Another good thing is that Cortef is an inexpensive drug.  If I have to fill an RX that does not go through my insurance company then it will not be too expensive for me to pay for on my own.