Hello Cindy and Butter. So glad you found FDMB.
I know this is going to sound totally backwards but it sounds highly likely that you need to reduce the dose of insulin immediately. Changing insulin with the dosing method your vet is using is not going to make any difference whatsoever. This is all too common and you are not alone in this experience. Many of the folks who find us are here for exactly the same reason.
The starting dose of insulin would normally be around 1u twice daily so your vet prescribed double the usual. We recommend dose increases be done in 0.25u increments and definitely no more than 0.5u. So again, your vet has been increasing the dose at least twice as quickly as we recommend. Our kitties are small creatures and 1u increases are huge making it highly likely that the best dose for Butter has been totally missed.
Insulin is not a medicine like Aspirin where if one tablet doesn't work you take two the next time. It's a hormone that triggers other processes in the body and what is happening with Butter is perfectly natural. When the BG starts to drop too fast and/or too much, all mammals have a defence system that triggers various processes in the body to spill stored glucagon into the bloodstream and bring the BG back up to safe levels. In Butters case, his body has become used to higher than normal BG and so his defence system gets triggered prematurely and panics raising his BG up even higher than what has become normal for him.
Now that you are home testing (KUDOS to you for that!) you can gain much better control over Butters than the vet ever could because the other problem at play here is that our kitties are usually stressed out at the vet and this causes temporary elevation of BG. Some cats will have a BG 100 or more points higher than their norm. This of course leads the vet to think kitty's BG is far worse than it is and they end up prescribing too much insulin.
Now that you are home testing, it would be very helpful if you would set up one of our spreadsheets to track Butters BG. The spreadsheet is viewable by members here who can help you get Butter on a better path and on the road to feeling and acting much more like his old self. If you can plot in the readings you have taken at home so far, it will give folks here some data on which to offer more specific opinions/suggestions. Here is a link to the
Spreadsheet Instructions and another link to
how to use the spreadsheet. If you need any assistance setting up the spreadsheet, just holler and someone will help you out.