You switched on 10/11? It would be helpful if you added the date you switched to your signature.
Lantus takes an entirely different mindset than Prozinc. With Prozinc, because it is not a depot insulin, you can adjust your pre-shot dose without the same effect on numbers that you will see with Lantus. Lantus dosing is largely based on the nadir. We typically recommend that if you get a lower than expected pre-shot number, that you post and ask for help.
The insulin depot is unique to Lantus and Levemir. When Lantus is injected, it forms microcrystals that are deposited in the fat tissue. Those crystals slowly dissolve. Not all of the crystals dissolve by the end of the 12-hour cycle. Instead, they overlap the next cycle which is what gives Lantus its long duration and ultimately, flat cycles. If you look at the spreadsheets of cats that are on OTJ trials, you'll see a lot of green numbers. It takes about 5 - 7 days for the depot to stabilize. It also means that with Lantus, you don't want to make back-to-back changes in the dose. Depending on which dosing method you choose to follow, doses are changed after 3 days/6 cycles with Tight Regulation or after a week with Start Low Go Slow (SLGS). Every time you make an alteration in the dose, it has an effect on the depot.
What you saw on 10/11 is fairly typical of an insulin switch. Your cat have a marked response to the new insulin. Numbers dropped and then you saw a bounce. It can take roughly 3 days for the bounce to clear.
So, at this point, I'm not sure exactly when you started Lantus and how long you need to hold the dose. I'd encourage you to read over the sticky notes at the top of the board. It will help you to wrap your head around the differences between Lantus and Prozinc. And please, ask questions! We're here to help.
