I was able to check his sugar and it was 236 at 8pm.
How long after the last shot?? Was this just before insulin?
Novolin is a fast acting insulin, I'd aim to try and get a test at around +4. That will start to give you some idea of how much the dose is dropping his BG by. This in turn will help you answer the question of 'Is it safe to give XY units?'
If you are able to at the weekend do you think you could run a curve at home??? Cheaper and more reliable than having it done at the vets.
A note on bouncing
Sometimes too much insulin can look like too little - see somagi effect (bouncing)
(when we talk about bouncing, this is not the same as somogyi effect, which has since been disproven in humans, and never even studied in cats),
- Bouncing - Bouncing is simply a natural reaction to what the cat's system perceives as a BG value that is "too low". "Too low" is relative. If a cat is used to BGs in the 200's, 300's, or higher for a long time, then even a BG that drops to 150 can trigger a "bounce". Bouncing can also be triggered if the blood glucose drops too low and/or too fast.The pancreas, then the liver, release glucogon, glycogen and counter-regulatory hormones. The end result is a dumping of "sugar" into the bloodstream to save the cat from going hypoglycemic from a perceived low. The action is often referred to as "liver panic" or "panicky liver". *Usually*, a bounce will clear kitty's system within 3 days (6 cycles) (this is taken from the Lantus sticky, not sure if length of bounce is the same with different insulins)
That said too much insulin can indeed look like not enough, in order to figure that out, it'll be necessary to run some curves and get some midcycle tests, teaching your grandmother or uncle how to get those tests will be an invaluable help to you. They wouldn't need to be keeping syringes in the house to do that, so perhaps theres a possibility of you doing the amps and pmps, and them helping you with those midcycle numbers.
No food for 2 hours before you first test, then shoot insulin. Then you feed.
Actually we usually test/feed and then shoot.
This is even more important with a fast acting insulin like novolin, I would make sure kitty is tested, then watch him eat and feed, you really don't want to be injecting a fast acting insulin into a cat that won't eat.
Lastly, I would encourage you to set up a spread sheet for recording the test data, I found this an invaluable tool for me, and also it gave me a way of presenting data to my vet.
Most of us set the spread sheet up and share it with the community, by doing this you'll be able to get the best help possible for your kitty. We are not vets and our advice is data driven, many of us are very accustomed to reading these spread sheets and tailoring the advice accordingly. As you gatther more data it will become an essential tool if you want to receive good advice from experienced members on the board.
Here's a link on how to set one up, (click on the highlighted text below)
Spread Sheet Set up Instructions