so I want to get his BG down asap. Is that even possible with an acro cat?
Absolutely possible. Each acrocat needs varying degrees of insulin, some higher than others. A few examples of nicely regulated acros, click on the link to see their spreadsheets:
Amethyst,
Freckles,
Crystal. Neko got there eventually too. One of the things you will notice in all of those spreadsheets is that those caregivers tested a lot more than you do.
The key to getting blood sugar down is to get to a dose that can lower the blood sugar. You do that by knowing how low the current dose is taking the cat and safely increasing. That means testing the preshots (which you are good at), but also getting more tests in the middle of the cycle, including at night. We determine how to change the dose based on how low it takes the cat, not the preshots. Based on those low points, the insulin dose is increased. We have a couple dosing methods used here by people using Lantus. If you haven't already, I would read the yellow starred Sticky Notes as the top of the Lantus/Basaglar/Levemir forum, including the Dosing Methods sticky note. Following one of the dosing methods here also allows you to increase much faster. The nature of insulin resistance, be it IAA and/or acromegaly, is that you can't stay at the same dose as long as you have been. We also increase by smaller amounts than you have been doing, in order not to bypass a good dose.
The latest catalog from Michigan State University shows the IGF-1 test as $65 and IAA at $20. On top of that your vet will charge for the blood draw, and there is the cost of shipping, which will vary depending on where you live. Some of the people here have been using the drug cabergoline with their acros. For some cats it reduces the effects of the growth hormone and resulting size of dose needed, if the cat has acromegaly. But first you have to test to see if that is what Bubba has.
You are commenting about weaker back legs. Is it possible he has neuropathy? People used Zobaline to help with that. Getting his blood sugar down is also a key to helping neuropathy.