Leeanne,
 
I have had several insulinomacs.  In my experience, if the cause of the
hyperinsulinism (too much insulin) is from a large node or two, and this
is removed, they can have as much as a year symptom free.  The symptoms
do recur, usually.  Some folks even repeat the surgery.  If, however, the
cause is tiny overactive cells, the vet can't tell which area to remove.
No improvement in our household there.  Treatment consists of diet,
prednisone and possibly diazoxide.  (am having a severe senior moment, am
not sure of that last drug, and we used it for over a year!) We have had
ferrets live 2 to 3 years with this disease.  One thing to keep in mind,
is he will need to have food available at all times.  I would forgo the
sugary treats, fruit and such.  Ferretone, ferret/cat treats work, if he
will take them.  Hand feeding his usual food even works sometimes.
 
Good Luck
[Posted in FML issue 4041]