For a kitty just starting out on Lantus he's getting a really good response early on. Lantus is a depot insulin so each shot builds on the next. Right now 2u twice a day doesn't look too bad, except that most cats don't respond this quickly because it takes about 3-5 days in the beginning for the shed or depot under the skin to build up. So there is a chance as it forms that the same dose may take him much lower than it is now. But that is where testing comes in handy, because it will tell you if he needs more or less insulin as you collect data.
Now to kind of explain what a shed is and how it works.
Think of a funnel and you're trying to fill it so the water stays level at the top of the funnel, the only problem is you haven't put a cork in the little bottom hole so the water is pouring out the bottom as you try to fill it to the top. The water you are pouring in is the dose you are shooting, if you pour too fast or too much the water over flows the top of the funnel (hypo), but if you don't pour enough or fast enough the level at the top of the funnel sinks, (hyper). So you have pour just the right amount at the right speed to keep the level at the top of the funnel even that matches the amount coming out the bottom that what is going in the top replaces. The water that is in the funnel it like the insulin shed. What you pour into the top isn't the same as what is coming out the bottom, what's coming out the bottom is what was already in the funnel before you poured the next dose in the top. Which is why we hold a dose for several days when we change it before looking to see if we need to change it again. It takes a couple days every time you change doses for that shed to readjust to the new dose.
Make sense?
Mel and The Fur Gang
