Welcome to FDMB!
It sounds like you were planning on reviewing the sticky notes at the top of the Lantus board. There's a huge volume of information there so let me try to underscore a few of the high points especially since I want to suggest making a few changes to what you've been doing.
I would check the carb counts on the Young Again variety you're feeding Karamelle. The variety that we suggest is Young Again Zero. They do have a Mature Zero so if it's that version, it's likely to be fine. If it's a "zero" formula, would you mind adding that to your signature so we don't pester you about feeding your cat a low carb diet?
Lantus likes consistency. The reason is that it is a depot type of insulin. (There's a sticky note describing the depot on the Lantus board.) One aspect of consistency is shot time. It's recommended to give your AM and PM doses as close to 12 hours apart as possible. It's best to stay within a 30 minute window of that 12 hour shot. The reason is that an early shot acts like a dose increase and a late shot acts like a dose reduction. Those variations have an effect on the depot so the amount of insulin is inconsistent.
The other area for consistency is the dose. Lantus works best if the AM and PM doses are the same. Again, this is due to the depot. If you give different amounts of insulin at each shot time, the depot never stabilizes and you end up with wonky numbers.
The reason we suggest syringes with half unit markings is that we adjust doses in 0.25u increments. Making dose changes in small amounts means you don't go sailing past what may be an effective dose for your cat. It's also a bit easier on the caregiver's nervous system since it lowers the risk for a cat to drop into low numbers.
@Diane Tyler's Mom - Not to contradict Diane but please don't "like" all of the posts. It swamps our Alert box. For those of us who are checking in on a lot of members, I'd never be able to get through all of the alerts in a timely way.