I'm no where near being a vet, but I do have some experience with
insulinoma & dex.  I was given dex to use only in case of a crash.  It
is my understanding that this steriod is strong and fast, but very short
acting.  So probably not the best thing for maintainace.
 
After a bad episode last week, my Yogi was also given something more
long-term, called vetalog.  I don't know the chemical name.  This stuff
was like a miracle--she ate without fighting for about four days running.
I was trying to talk my vet into using that for maintainace.  Their
objections were that there could be side effects.  The main example?
wasting!  Well, I'd say not eating will have that side effect much
faster.  They had just agreed to try it (no more than 2x week) when Yogi
went into a foaming seizure that we couldn't pull her out of and died.
It wasn't the vetalog, which had worn off, but her own body that did her
in.  Still, if I ever have a ferret that badly off again, I'll go for
the vetalog much sooner.  It really was a wonder.
 
--Clover
and the rezweezils: Buddy, Cookie, Yogi, Butter, Buster (aka Fatboy),
Lew, and Marissa
"Always selling quality bedding and other goodies to help the ferrets!"
http://search.ebay.com/_W0QQsassZwclovergalQQhtZ-1
[Posted in FML issue 5229]