Hi Barbara,
Occasionally we'll see a cat drop between +11 and +12 on Levemir, after having already nadired. We have even considered Lev capable of causing double nadirs. It could be do to the nature of its action, that maybe some of it got hung up on the albumin or something and all of a sudden it releases. (No, I am not a chemist and have no idea how that would happen, but I welcome a better explanation for the phenomenon)
I don't think that's what happened today for Thumper though. It's literally all because you shot 40 minutes late. There was no overlap left and the late .25u dose just couldn't catch up.
So I think it's well worth staying with .25u for a few more days. I think she will eventually even out at lower BGs. I hope today's action after the 175 convinced you it would have been safe to shoot the .25u at that BG level at +12. Levemir has a slow onset, so she probably would still have been 242 3/4th an hour later even if you'd given the shot. That's why it's important to get those early BGs or to wait and test again later on a low preshot in the beginning so you can see what happens with insulin or without insulin and feel more comfortable shooting those low preshots. They need to be shot in order for Levemir to work properly.