A few years ago, 18 pound indoor tabby developed a "rasberry" on
his chin, perhaps from rubbing on the edge of the fridge door
expecting the roast chicken bits to appear.  He gets his usual
Science Diet weight control wet and dry food.

Off to the vet, they tried antibiotics, didn't improve so they gave
him a series of steroids.

Urine output went through the roof and we discovered the world of
permanent steroid induced diabetes, vet had no clue about this.

He responded well to two units of Humulin insulin a day for years.

Many months ago he developed what might have been colitis and we
almost lost him, they couldn't really track down what the problem
was and we spent a fortune with them more or less turning up no
definite problem.  But he recovered with a lot of care and looked
like he was back to normal.

A month ago it looked like ear mites, "coffee ground black grit"
in one ear.  Off to the vet, he did a swab, said it didn't look
like mites to him, especially since he was indoor only, well he
does get onto the enclosed balcony and neighbor cats do get in there
where they growl at each other from opposite sides of the screen
door, but they are never in contact with each other after one
confrontation years ago.  But, vet gave me a bottle of stuff that
he said would deal with it if it was mites and would deal with it
if it was anything else.

I put drops in each ear for a week.  At the end of that his urine
output went through the ceiling, new record levels!  So I asked the
vet if the drops could possibly be the cause, nothing else had
changed or been done.  He said no.  I searched the web for the
contents, one antibiotic, one something else and dexamethasone, a
potent steroid.  Dexamethasone can induce whole body insulin
resistance, even when applied topically, one vet pharmacutical web
site says "do not give this to diabetic animals unless there are
life threatening reasons to do so."  But doesn't give any more
information than that or give any idea what the consequences will
be.  Again ask vet.  Again he said this couldn't be it but he would
check.  Blood glucose test done and sugar isn't wildly high, but
he is drinking up to 4 cups of water a day.  Then the vet changes
his mind and thinks the dexamethasone was the cause.  And the cat
has bouts of diarrhea, something he has never had.  Now the vet
doesn't know what it is but doubts the dexamethasone.

So, web searching for dexamethasone describes this inducing diabetes,
describes symptoms of diarrhea, possibly this is iatrogenic Cushing's.
Says that gradually weaning a cat off steroids is best, but the
drops stopped weeks ago before we even knew this was perhaps related.
Some claim that a month or two and the adrenals may recover.  But
this has been more than a month now, he is drinking over 4 cups a
day, he is very slowly loosing weight, something he has never done,
even though he is being given a little more chicken in addition to
his usual food.  He isn't grooming as well as usual.  But he hasn't
developed "fragile skin" which is one symptom of severe adrenal
problems, although we are being much more careful about brushing now.

So, he appears to be slowly getting worse, rather than slowly
recovering from the dexamethasone.  Vet just doesn't know what it
is.  Anyone have any ideas?  There are adrenal function tests but
they say they aren't really conclusive and they involve giving him
more dexamethasone, among other things.

Thanks