Just wanted to say that if you are not testing at shot time, that's risky business. In the past month, there have been at least two kitties on the board that have died from hypo's, one just last night. I know that in at least one of the cases, the shots had become routine, and the morning in question, no test was taken. The poor woman came home to find her kitty almost comatose, and the ER vet was not able to save her.
When you have been getting +6 readings near 100, that doesn't leave you too much wiggle room if for some reason kitty has a better than normal response to the insulin. Without knowing for sure what his BG is at shot time (what if it's 100 points lower than you think it might be?), the dose could be too much. I know his ears are taking a beating, but I would rather see sore ears than a hypo...
Neither the pre-shot test, nor the nadir test are really wise to skip, but if you have to pick just one to test, it should definitely be the pre-shot. If you get a low number, you can reduce or skip the shot. But once the insulin goes in, there's no taking it back out. Please, for his safety, reconsider not testing before ever giving him a shot?
Carl