I guessed that's why you dropped him. What we often see is when the insulin dose finally gets high enough to provide some action and a cat's blood sugar gets into better numbers, people drop the dose. Then the lower dose puts them back into high numbers. It's what's happened to you and petey.
If you want to work towards regulation and/or getting him off of insulin, your goal range is 50-120. If you can't monitor, then ya gotta do what you gotta do to keep him safe, but if you drop a dose because you've got a lower preshot and you have to leave him/go to work, typically you go back to the normal dose at the next shot. Lantus works best on lower numbers - if you start with a preshot in the 90's, you may see him spend the next 12 hours between 50 and 90.
I'm not saying to shoot the full dose into green numbers when you have to leave the first time. You have to be able to monitor.
However, you want to gather data on him so you can work up to that. Definitely you need to be able to monitor when you shoot low, until you have confidence (based upon data from doing it when you could monitor) on how he will react to the shot. Here's a post I wrote recently explaining a little more about
shootling low. There is a section on the "Shooting and Handling Low Numbers" sticky (with a yellow star at the top of this forum) that explains how to become "Data Ready" to shoot your full dose into normal numbers: 50-120. That's the path for getting a cat tightly regulated (kept in normal numbers) to protect their body from the ravages of high blood sugar, or ideally, to go off of insulin and become diet-controlled.
There are a lot of people who order from Canada - I'm not experienced at that but Chris/China has info about a pharmacy that she uses.
As far as his behavior, it's not unusual for a cat that's gotten used to high numbers to look like they feel crappy when their blood sugar gets back into normal ranges. The cat's body has developed
Glucose Toxicity. They've accepted the high numbers as normal and then the lower numbers feel like a hypo to the body. As a cat spends more time in normal numbers they'll get re-accustomed to the normal numbers. I think of it like a person who is used to several cups of coffee every day will feel gross when they skip their coffee, although coffee-less is their natural state. Eventually you get used to it though, and then often people say they feel even better.
Not sure why he's feisty - when you say that do you mean he's starving? High blood sugar literally starves a cat. The energy from the food they eat (glucose) is circulating in their blood and not able to get into their cells.