Hi and welcome to FDMB :mrgreen:
Not sure if you have called into Lantus forum, so will reply here anyway.
I can see what Monique is saying but also want to point out (cos I'm guessing you've been thrown by the sudden jump in numbers).
I wouldn't put it down necessarily to kitty's food.
He went missing for a week-which means he went with out shots for a week? That would also mean that his shed emptied. Lantus builds up a shed over time (like a petrol tank-forgive me if I'm teaching you to suck eggs), which means it can carry on working beyond 12 hours.
Lucky had an excellent shed and on a few occasions (this is not recommended) had no choice in terms of her stress levels but to miss a shot (rather than go in vets for a w/e and be shot with people using welding gloves!! for 3 days).She could still hold her numbers as if she hadn't missed a shot.
Must say, this is extremely rare.
My point is, that your kitty's shed of insulin may have kept him going and the climb up hasn't been too quick.
I would stick with the .75u for at least another 2 days. Try and get the preshot tests and one or two between 4-6 hours (appreciate beans have to work but maybe you don't work week ends so at least would have tomorrow?).Your looking for kitty's nadir (lowest bg number in a 12 hour cycle) this is what you base his dosing needs on, not the pre shot number (this comes into play if kitty throws a low number and you need to delay shot or give a reduced dose-depends on number, bean life, kitty etc)
Then beans in LL (maybe you if your confident? again not being condescending, we get a lot of lurkers here who never post but take info away.Ethos of this board is to never cause harm to any kitty

)can help advise ypur next step.
Plus! we're a friendly bunch :mrgreen: