Hello, I am new here aswell but have learned so much from members and reading stickies.
My cat Shishi was in a similar situation to Lucky's. Worked up the dose from 1unit to 6units usually with no results, Shishi seemed to stayed in the 300-400 BG's.
The problem that I had was Shishi was eating prescription wet food, and also some Dry prescription kibbles which were both high carb food. After I ditched the vet food and all
dry food, and switched to a low carb wet food (less than 10%) 4 days later Shishi started to respond to insulin. Take a look at my SS and you can see the dramatic change.
Shishi did not take the change very well and started to look for other sources of food, I had to close doors to the kitchen at all times and make sure that I did not leave food where she could access them. she was especially sad that I had to cut out dry treats aswell. I have since moved her to low carb treats, Freeze dried chicken.
What I am trying to say is if Lucky is on a strict diet of low carb foods, then just be patient and follow protocol. But if Lucky has dry food anywhere, it might be a good start to ditch all those high carb and dry food. Food is really important, and can be manipulated in many ways to keep the BG's in a good range.
Here is a link on Janet and Binkys food list and cat nutrition. These were especially helpful to me.
Janet and Binky's food list
Feeding Your Cat: Know The Basics of Feline Nutrition
Here's a link on how we usually use lantus. These are stickies on the top Lantus/Levemir group on this site
Tight regulation protocol
LANTUS & LEVEMIR – INSULIN DEPOT –AKA- STORAGE SHED
Lantus&Levemir – Data Ready to Shoot Low Numbers
If, Lucky is eating any dry or high carb food now, and its scrapped, there is a good chance that the BG's will come down. And you want to be prepared for if any HYPO (BG too low) symptoms occur.
List of Hypo symptoms
How to treat HYPOS – They can kill! Print this out!
Jojo’s HYPO TOOLKIT
Best of luck.