Interesting. Sometimes he bounces and sometimes he doesn't. How does food figure in? You might give him a little snack around +3 to see if he flattens out and surfs along in lower ranges longer. Does he eat the same %carb food daily or are some days higher carb than others? (Some cats are very carb sensitive and even the difference between a 3% and 7% ups the numbers.)
I'm sure you've heard us say that cats bounce until they don't. (I think the record was a Lantus kitty who bounced for 2 years). The good news is that his numbers are in good ranges most of the time (anything under 250 is supposed to allow the pancreas to heal). I think you're doing great, adjusting the doses to fit his numbers. Surely he'll get used to the blues pretty soon and level out.