Levemir is a great insulin, too, and Wendy is correct.....it does not sting. Lantus seems to sting more the higher the dose although I never got to more than f1.25u with Gracie on lantus and it stung so ECID.
One of the great things about lev is the later onset...typically around +4 so it allows you to shoot low more consistently and still have some time before the next shot onsets. You need to consider whether the late nadir (+8 to +12) would work for you.
Switching to lev is not a guarantee that Tiggy will flatten out. Some cats like Tess, Putty, Pats Shadow, Checkers still bounce quite a bit. While Gracie still bounces, lev has flattened her out more than I could ever get her on lantus. Take a look at some of the SSs I mentioned as well as Alex, Libby's Jazzy, Rustyy, etc....all lev cats. jazzy was acro.
Perhaps you want to wait until you can get the tests done, and see the results before you switch? If not, let me know and I can give you more info.
eta: I do think it's worthwhile to consider switching him. It's been over a year now that you've used lantus and sometimes a change can help. If you aren't going to have him tested anytime soon, then I'd give it a try.
