I can't see from your signature line what glucometer you're using? Is it a human glucometer? I think so, so all this below assumes that's what you're using.
Here's the reference from SLGS:
After 1 week at a given dose perform a 12 hour curve, testing every 2 hours OR perform an 18 hour curve, testing every 3 hours
Note: Random spot checks are often helpful to "fill in the blanks" on kitty's spreadsheet.
- If nadirs are more than 150 mg/dl (8.3 mmol/L), increase the dose by 0.25 unit
- If nadirs are between 90 (5 mmol/L) and 149 mg/dl (8.2 mmol/L), maintain the same dose
- If nadirs are below 90 mg/dl (5mmol/L), decrease the dose by 0.25 unit
- As your cat's blood glucose begins to fall mostly in the desired range [lowest point of the curve approaching 100 mg/dl (5.5 mmol/L) and pre-shot value around or below 300 mg/dl (16.6 mmol/L)], do lengthen the waiting time between dose increases. If you decide to change another factor (e.g., diet or other medications), don't increase the insulin dose until the other change is complete (but do decrease the dose if your cat's glucose numbers consistently fall below 90 mg/dl (5.0 mmol/L) as a result of the change). Don't be tempted to rush the process along by increasing the dose more quickly or in larger increments-- no matter how high your cat's blood glucose is! Rushing towards regulation will cost you time in the long run, because you may shoot past the right dose.
Lather, Rinse, and Repeat!
I think it's a little ambiguous in your situation. For choosing to adjust the dose, I'd go by the lowest point in the past few days on this dose, which was 149. Right on the border between the "hold the dose" and "increase the dose." Overall, I agree with you - i think she looked better at 1.5u.
If you didn't test so much, I might suggest holding the dose. Most people use SLGS because they are feeding their cat dry food, or because they can only test occasionally. In your case, it's pretty clear what's going on in Ivana's body and you can see nicely how she's doing with the dose.
When you decrease the dose, the idea is that the good nadirs continue - in Ivana's case, it looks like the dose reduction has taken her out of green numbers. So based on that, I'd go back up to 1.5u immediately. When you've taken a dose decrease because the cat dropped below the reduction point, and then the cat's blood sugar trends up, you don't wait x number of cycles to increase. That's considered a failed reduction, and as soon as you determine that the reduction failed, you can go right back up to the last good dose.
When you're initially increasing the cat's insulin dose, it's important to hold the dose the appropriate length of time (and not rush things) before increasing the dose again. That's the time to not hurry things and make sure you don't overshoot a good dose.
Does that make sense?