I shot my diabetic cat up for six years (she wasn’t supposed to live long b/c the disease was so out of control: ha!)
I was very freaked out at first, but it became routine and very easy. As far as traveling, you can hire a pet sitter to come over and do the shot or, perhaps even better, board kitty. Kennels usually charge a small amount for shots.
My Friday is diabetic. The best resource that can be found (which I actually found here) is here. It’s a very easy thing to deal with, and I would highly suggest learning how to hometest, etc. per the suggestions you will read on that board. You may have a more challenging time if your kitty is adverse to being handled extensively, but there are ways to work around it. I’ve also found that my cat doesn’t really need a rigid structuring of her shots, so there is leeway.
Feel free to pm me with any questions, I’m more than happy to help guide you through all this.
Agreed: most cats don’t need the shots exactly 12 hours apart (or whatever the vet suggests). I found that so long as K-Kitty had enough units per day, she was okay (YMMV and IANAVet).
I also want to add that I thought my vet was over-zealous about all the testing once we established the amount of units that worked well; it’s the testing that becomes very expensive, not the insulin and syringes. Like Cherry, I started doing home-testing and cut my vet testing down by a fourth.
BTW, once you find a pharmacy that carries Humulin, ask them to order ahead for you. Humulin is old-fashioned insulin and pharms are tending not to carry as much as they did in the past.
Also feel free to PM me if you want to chat. Like I said upriver, it can be kinda freaky and squeamish at first, but it becomes routine and not-a-burden once you find some kitty sitting help.