Also, is it likely we are going to have to monitor him closely for years like you have your dear kitty and several others whose glucose charts I looked at? How do you deal with the constant emotional roller coaster, cuz I already feel like I am on one? Up and hopeful when he feels better. Torn apart when he is worse.
This is definitely an "every cat is different" thing. Some kitties are switched to low-carb canned food, and quickly improve, needing no insulin, or very few days on insulin. Some, like my cat, go into remission in a couple of months or so.
Some cats will never get to "remission", but can live long healthy lives regardless (just like human diabetics can).
I am fairly certain that for people like Sienne who have been doing this for years, it's not a big deal at all. She isn't tied to treating FD like it's a ball and chain around her ankles. It's just what life is like for Gabby. Others have treated their sugarcats for longer than that. Some here have done this with 2, 3, 4 or more cats, not because they have to, but because they choose to. They adopt diabetic cats, cats who might otherwise be put to sleep because their caregivers couldn't do it for whatever reason. Lots of them are rescued from shelters.
All of us ride (or rode) the same emotional roller coaster you mentioned. Some kitties go off of insulin, and then for some reason a couple of years later, they end up "back" to being insulin dependent. I guess we all sort of just roll with the punches. Personally, I have come to believe that Bob becoming diabetic was a blessing in disguise. It might not have been the best thing that ever happened to him, but it's been the best thing that's happened to me for quite some time. It changed my life, and all for the better in hindsight. I sure didn't feel that way when the vet said "your cat has diabetes", though.
I have a question about the nadir. Is the most recent nadir the important one in making an adjustment? Is it the nadir for the whole period of time or the most recent nadir that decides how much to increase in dose?
That depends on which protocol you elect to follow.
In the "tight regulation protocol", it would be the most recent nadir that determines a decrease in dosage. Because you would decrease the dose any time you got a nadir under 50. And as far as increasing dose, it would be an overall look at the past 3-5 days of data. If the numbers haven't improved, it would indicate an increase is called for. Adjustments would be in increments of .25u, except in rare cases when .5u would make sense. That doesn't seem to happen very often from what I've seen.
Following the "start low, go slow" protocol, it's more of a look at a whole week of data to evaluate the dose.
Each protocol has very clear "conditions" for increasing or decreasing dosage spelled out.
With the lowest nadir you've seen for a week being today's 225, I would say that an increase of .25u is the way to go.