That is possible.. But i have done a smaller dose and his BS never gets any less... He just doesn't bottom out.. Last night his Bs was 568!!totally insane. I cannot seem to regulate him anymore and it's driving me insane!!!!!!
When you say you lowered the dose, do you mean you lowered it for one dose or do you give the reduced dose for a few days to see how it is working? If you are just reducing for one dose and then going back to the higher dose, it's not going to make getting Miel regulated any easier. It will simply make it that much harder for you to figure out what dose is ideal for him because you are never seeing the true effect of any given dose.
Based on what you've told us, and knowing Miel has had one hypoglycemic episode fairly recently, that lead to a seizure, it sounds like he's on a continual roller coaster ride of high, then low, high then low BGs and that in itself is no doubt causing Miel to feel very unwell. Those ups and downs may be Miel's natural defence system working to keep him from having another serious hypoglycemic episode. That defence mechanism will eventually get worn out and be unable to bring his BG back to a safe level. The longer he continues to experience massive BG fluctations the higher the risk of Miel suffering another seizure and I know you do not want that to happen.
You've indicated this never happened before but Miel's insulin requirements may have changed for some unknown reason. Lots of things can effect BG and that is why we test before each shot to make sure it's safe to give insulin and then try to get at least one test in each 12 hour cycle to see how low the dose of insulin is taking the cat. If you get a pre-shot test before each shot and one mid cycle test whenever you can, then you'll be able to see how far and fast Miel is dropping on any given dose of insulin. Only then will you be able to figure out what dose is optimal to keep Miel in a reasonable BG range and keep him safe.
It's obvious you love Miel and equally obvious that the problems you are encountering are very upsetting for you. We would love to help you get Miel sorted out. I know you don't want to make a spreadsheet and I respect that but I hope you will give it a little more consideration and maybe just give it a try because without some history to look at, the folks here can only offer you generalized guesses as to what might be happening with Miel.