Thank you all so much for your support and suggestions. I googled feline diabetes as soon as we got off the phone with the vet and this is the first place it brought me.
Beef was left by an old roommate of Bryans as collateral, for a while when beef first moved in we would tease and call him beefcake because he was huge. And.when he was left the name stuck, new name for a new beginning. He had been maltreated by his previous owner, not fed properly it taken care of well. He is a very sweet fella I couldn't imagine not taking care I'd him let alone leaving him as collateral over 3 years ago, with no word since.
As for his diagnosis, he had been lethargic for about 2 weeks, but we're in the northeast and have been in a heatwave. Beef doesn't fair well in the heat so we chalked it up to that. He was constipated last week which happens every few months, so we give him a can of wet and systems are typically a go after. But it didn't help, and he began to have a little mange on his tail and wasn't cleaning himself well. We got a last minute vet appointment Saturday morning. He was really good during his exam but he had a fever and the vet gave us the option of an injection to hydrate him take him home and we'd come back on Monday to do the blood work or leave him to have an IV and they could get started ruling thongs out and work on a diagnosis. It was the first time he has not been in our home in 3+ years.
I guess our vet is pretty good. She gave us options and made almost the same recommendations you all have...kitty atkins diet (as Bryan has called it), not worrying about his diet until his blood sugar is stable, and home glucose readings to save on office visits. Right now he eats an indoor geared for tubby cats dry food, the name is escaping me, good life may be? The insulin was $100 for 40 units and for now we're going to try 1 unit am+ 1 unit pm. That's going to be the tough one.
Bryan and I are now both proficient in injections. He's having a harder time than Beef who doesn't flinch. But I'm sure I'll have my.moments too.
Thank you all again for the tips and support,
Lauren, Bryan, and Beef