Sounds like you are talking about Lysodren.  Yes, lysodren will lower
cortisol levels which will lower the blood glucose level.  Not a good
product for adrenal gland disease and especially not if they have an
insulinoma.  Jerry Murray, DVM
 
[Sukie note: Lysodren is very variable in effectiveness and can cause a
dangerous degree of atrophy in some while doing nothing for others.  It
also lowers blood sugar so if there is insulinoma (known or unknown) it
will worsen the situation and become dangerous that way, too.  15 or so
years ago we were among those who used it because options didn't exist
then -- unlike now.  BTW, 15 years ago was also before it was known that
Cushings is very rare for ferrets and that most ferret adrenal disease
is hyper-estrogenic.  Sorry for rambling; I am sick and not able to be
succinct.]
[Posted in FML issue 3416]