It's usually best to avoid feeding in the second half of the cycle.
From around +6 the amount of insulin in his body is waning, so feeding as the insulin levels are dropping can result in elevated BG at the end of the cycle.
When George was on insulin, I could feed up to about +7 (usually I was done by +6) with little effect on the latter part of the cycle. But some kitties are more sensitive than others.
You want to feed the majority of his cycle allowance in the first half of the cycle. So that he has food in his system to counteract the insulin as it onsets (typically at around +2) through to around +6, when the levels of insulin are at their peak.
After much experimentation I opted to feed 1/4of his daily allowance at PS, then 1/12 @ +2+4+6(am and pm), I used an autofeeder so I could have some freedom and get some sleep.
I found this worked better than what I was originally doing , which was feeding amps. +6 pmps and +6.