Hi...I'm certainly no expert in diabetes or a vet but after reading your notes, I have a few questions:
- Why are you giving him fluids, because of the constipation?
- What is his BUN and Creatinine?
- Why valium?
The reason I'm asking is because, while clearly he is diabetic, all of his symptoms sound like CRF (chronic renal failure). That sounds worse than it is so don't panic. I'm just about an expert in that disease. The bad coat, the constipation, the diarrhea are signs of CRF. I'm also concerned that he's ingesting so many different products, from different antibiotics (but no mention of a real infection) to all the other things you mention. The antibiotics alone can cause constipation in some cats. Carafate will sooth the digestive track but too much can also add to a constipation problem. Miralax is a miracle drug for constipated cats and don't be afraid to increase the dose. 1/8 tsp may not be enough. Try 1/4 tsp. If his poop gets too soft, back off the amount.
To me it sounds like your cat's digestive system is being over loaded and you need to unload it. The first culprit I'd suspect would be his food. I'd cut out the dry completely. In lieu of dry treats, you might want to try "Pure Bites" soaked in water. Zero carbs.

I'd also suggest trying raw food. My personal favorite is Rad Cat. It's fairly expensive but so are vet visits. At least give it a try for a week and see how William responds to it. You may need to sprinkle a little bit of Forti Flora on it at first if he' doesn't take to it right away. All but one of my cats dove right in but even she did with a little Forti Flora on it.
Here's why I suggest raw food...
I had a cat who had a reaction to a Rabies vaccine and had horrible diarrhea for weeks. Nothing the vet or I tried helped and he was losing weight rapidly. I combed the Internet looking for a solution and kept coming across articles about raw food. I was desperate, so even though I was scared to death to give him "raw" food, I did it. Within 24 hours the diarrhea stopped. My vet who was totally against the idea at the time, is now a proponent of raw food diets.
My CRF cat had less than 10% of her kidneys functioning and thanks to Miralax and raw food, she had 3 wonderful years
without supplementing with sub-q fluids. Basically both she and I had a stress free life. She wound up with CRF because of an emergency vet who gave her not one but two drugs that he never should have given a cat. HE put her into acute renal failure.
I'll get off my soap box now about raw food...I'm in favor of canned food as well.
As for your original question, have you read the "
Start Low, Go Slow" approach. It will guide you through the decision to increase or decrease the insulin. It's incredibly helpful. The one thing I try to keep in mind is that while we all want that perfect number, too high is better than too low. If you'll look at my cat's SS, you'll see her numbers are high. While I am concerned and doing what I can to get them down, I also have learned not to become obsessive about it either because that's not good for you or your cat.
Lastly, for his skin wound, have your tried Vetericyn? It's a wonderful product and easier on the skin than Chlorhexidine.
I hope this info helps.
