Hi Celia....Welcome to the Lantus boat and the FDMB. You'll find a wealth of information here and people who care about you and Loki. This is a very busy place, as you can see, so make sure you have all the information in your signature and your thread so the more experienced members here can tell what's going on at a glance. You'll want to put the date, Cat Name at least an amps # and, in this case, your question. (i.e.: 8/19/Nova-amps 254--question about yada yada...) Use the prefix of a question mark too.
I'm not an expert, but I can say it is very hard to tell if lantus is the right insulin for your cat because, quite frankly, you really do not have enough data to tell yet. From what I see on the spreadsheet, you've only been dosing for 3 days? It takes time for the lantus depot to fully form, and it takes even longer for your cat to adjust to receiving insulin, hence the bouncy #s.
Lantus works best when given at the same dose, at the same time every day, until an increase or deduction is needed based on Loki's lowest reading throughout the cycle in a period of time. To use a sliding scale based on any given shot, especially before giving insulin is not the way to go. I do want to give you many kudos for testing Loki.....you are keeping him safe.
Please read the stickies at the top of the lantus forum, especially the dosing methods, and the Basics. And read any and everything else you can when you have time.
I'm sure someone else will chime in when they can. Hang in there and remember...dealing with Feline Diabetes is a journey....for some it's a short one, and for most others there is a long road ahead with many forks in the road.