This is a tough one. A few days ago, 6.5u was almost looking like too much with that 59. I'm gonig to think out loud here for a minute, so this might get rambly....
Sooooo.....he is either:
A) getting too much insulin and bouncing by the PS's
B) not getting enough insulin so his PS's are rising
How's that for helpful? It's either too much or too little
Today's cycle could be a flat cycle after going too low. And your PS numbers could be looking ugly because he's dropping hard in the middle of a cycle somewhere and then dumping glucose to keep himself safe - which gives those ugly PS's.
Or....those reductions were just some little wobble in his journey and he needs you to raise the dose up again.
Or....those reductions were real, but something new has cropped up like a bad tooth or a UTI that has all of a sudden pushed his numbers back up.
My hunch is that he needs more insulin. The reason I'm leaning that way is that on the earlier cycles when you were at 8u, then 7.5, etc., you could see hints that it was too much insulin with the PS numbers going up and down. Right now they are just steadily going up. There's some variation, but not much.
It does seem weird that he'd be going down for a little while, and then suddenly reverse course though. Which leads me to think there might be something going on with his health in some other arena that is impacting this. But again, it might just be one of those things. Cats are weird sometimes.
So what should you do? I think there are two main choices right now:
1. You could try moving him back to 7u and see how he does. If it's too much insulin he should start to get wonky PS numbers again.
2. You could wait a couple more days, and keep getting mid-cycle numbers from a few cycles in a row to try to either catch a sneaky low number, or "prove" that the mid-cycles are all too high.
The safer option is #2, but in the middle of farming season, I don't think #1 is a terrible choice, as long as you leave some food out for him while you're away all day.