Hi Kate,
My condolences on the loss of your friend. We have had so much loss on the board lately, we know how difficult losing either human or pet is.
For Tigger, here's the thing about Levemir. You can give too much for a considerable amount of time and not see evidence that the dose is too high. This happens on Lantus too, so the vet is still not right about Levemir being so much more potent, but I do call it the Gentle Giant. Instead of dropping them to the basement on the first too large dose like a faster acting insulin might do, Levemir can produce BGs which look for all the world like the dose is not high enough. Then Bam! Out of the blue you have a drop-out like this morning. There's your proof that 2.25U is too much, and honestly from what we've experienced, even 2U is too much.
Levemir works best using a step up approach, that's why the Tilly Protocol works well with it and Lantus, as Lantus is similar in this regard. It is so much easier to start with a dose below their optimum (which you don't know) and work up if needed. That is what you thought you were doing. Unfortunately, 2U is not far enough below the optimum.
Because we have seen cats do so well on doses of less than 2U of Levemir, I highly recommend dialing all the way back to 1U and essentially starting over. If there is no sign of infection and he's eating well, that would be fine. Yes you will get BGs that look all the world like not enough insulin, but they should level out and not do this bottom dropping anymore and you can increase dose after 5 days, if needed. You can't continue with a dose that produces a 44 at +12.
And I have no idea if the Convenia is related. That would be a variable in this case, so I would definitely watch his behavior over the next 24-36 hours. If you think he received it previously, he's probably OK, but best to be aware.
