Yeah, that looks like a bounce!! They're very frustrating, but the more time he spends in normal numbers, the more likely his body will be to learn that it's OK to be there again. By the time our kitties are diagnosed, they've usually been diabetic for quite some time. Their body has gotten used to living in those higher numbers so when we "force" them down with insulin, the liver thinks there's something wrong and over-reacts by sending stored sugars and hormones to bring them back up...they "bounce". All you can do is keep trying to get him into good numbers and hope his body learns to accept those good numbers as normal again. Usually they do eventually start to accept the lower numbers and they won't bounce as high and they'll clear the bounce quicker.