He's actually leveling out some, at least getting 100s later in cycle and last night's preshot was pretty good.
Although we use 3 days/6 cycles as a guide for how long to hold dose, some cats need longer at a particular dose for things to level out. He is still working through the ups and downs of previous doses, affects from a particular dose can last 3 cycles at least when you've had as much bouncing going on as he's had.
Progress on Levemir is less extreme ups and downs, especially if there's a possibility the cat has been receiving too much insulin, as the extremes between highs and lows suggest here.
Sorry if that differs from other's suggestions but it's better to look at the whole cycle on Levemir, not just nadir.