Hi,
To answer your posts, the vet does run regular blood sugar tests. He had planned to close at 12 today but let me stay an extra hour. He was going to run a blood sugar test but was waiting til I left so as to give me the most time with her. Other than her behavior, given that she's on IV but not eating/drinking, it is an educated guess that the 1 unit of insulin was making her low (she'd had a reading of 80 at peak a day or two ago as I recall).
I am fortunate in that the vet lives where he works. So he will be checking on my cat at regular intervals, even throughout the night. When my childhood cat took a sudden turn for the worse a few years ago, he stayed up all night with him. At a hospital, while their hours may be longer, in the past they only let me stay around 20 minutes. With this vet, I've gotten to visit as much as 3x/day on his longer days, and when I had only one visit per day, it's often been for 2-3 hours.
Phosphorus binders only really work when given with food.... they bind to the phosphorus in food, but as I understand they will not take out phosphorus already in the cat's system. They also have side effects. My cat has only eaten twice in the past two days, when I was there, and not enough food. Thanks for the site, I will check it out. For awhile I was asking all similar types of q's, like did they test for this, and that, etc.... but given that my cat has been crashing every 2 or 3 days for the past 1.5 months, and had pulled out of it before, but isn't right now, and her kidney/phosphorus values are going way up, the feeling is that she is beyond the point where she can be helped. I will continue asking questions, but so far the vet has answered pretty well and had tested whatever I asked him about... I could pull my cat out and take her to a hospital to get a second opinion, but chances are it will cost thousands to hear the same thing (I've alraedy spent thousands on her since her DKA), and also, she is just so frail that I can barely pick her up.... I am afraid she wouldn't survive the car ride, and she may think she is going home, only to be driven to the ER and then back to the vet to be put to sleep.

That seems like a lot to ask of her. My feeling is that the IV either will flush her kidneys out or it won't.... and if it doesn't, she's in serious kidney failure and nothing can really help that.
My heart is tugged knowing she is where she is right now, without her mommy. I'm just hoping tomorrow she'll do well enough that I can hold off til Monday before making any decisions. Sometimes I wonder at my motivation because I may be being selfish given that she is not comfortable. I want to do right by her, and it's so overwhelming, because it's damned if I do, damned if I don't. I'd asked about a feeding tube, but the vet said he'd be very concerned she may not survive the procedure at this point, she's so delicate.