Thanks to all who have replied to my post yesterday.  I have some updates
from my vet (of whom I asked many questions today.)
 
He called my work to find out how P.B. was doing and plans on calling
again tomorrow.
 
He tells me that typically insulinomas are pin-sized and so the x-ray
taken of P.B.  wouldn't necessarily discount that possiblity.
 
The reason the low blood sugar is a bit of mystery is this: Each time
P.B.'s blood sugar is found to be low, his insulin levels are at a normal
level.
 
In any case, the shot that he was given yesterday was Depo Medryl (sp?)
which is a progesterone type steroid released over weeks.  He prefers it
to daily prednisone because it can maintain glucose levels better.
 
He wants us to keep a very close eye on the booger to make sure he doesn't
have a seizure (little guy has had a couple, probably brought on by the
low blood sugar I guess) with instructions to call him at work or at home
if necessary.
 
To complicate matters, a highish level of clostridium was found in his
stool.  We have him on anti-biotics for that.
 
Thanks to all of you.  I appreciate the support, advice, and kind words.
 
Matthew in CO with P.B. (missing Sherlock and Gryphon)
[Posted in FML issue 3749]