Frustration is absolutely normal in the beginning. We all want immediate results; we want the numbers to come down and the cat to be all better. Unfortunately, we don't know how long that cat has been diabetic as some don't show many signs, or how well the ol' pancreas is working.
In the beginning, we are giving insulin to get down to the safer numbers; we want under that 240 mark. We give insulin and the cat's body is all of a sudden forced to feel different, to feel wrong. For so long, those high numbers were seeming right, so when you get down to the right numbers, those right numbers just feel wrong, very wrong.
We are causing a disruption with changing the diet and giving insulin and some kitties are kind of stubborn ... they just can't handle those better numbers quickly and so we have to go slow and be patient with them.
Don't worry; in time, you will SEE improvements in the cat, and eventually those improvements will be reflected in the BG numbers.
I wanted to give you some links.
The first 3 will give you some info on Lantus. I don't know how long you have been giving shots, but in the start, it's slow going to find the dose that finally shows on your cat in the numbers.
VERY IMPORTANT: you will see improvements in how your cat acts before you see the better numbers. The numbers can be stubborn for many reasons.
Tight Regulation Protocol
LANTUS & LEVEMIR – INSULIN DEPOT –AKA- STORAGE SHED
Lantus&Levemir – Data Ready to Shoot Low Numbers
I don't know where you are located, but removing ALL dry foods and treats is the best place to start regarding food, but I see you have already started - just get rid of all the dry as it's the cause of high numbers for some cats, including one of mine: Shadoe.
Binky’s Food Lists
Feeding Your Cat: Know The Basics of Feline Nutrition
Here's a method to convert your BG results:
BG Conversion Calculator
I am not sure if it's the most recent instructions but if not, others can help you.
Many keep track of their BG results on spreadsheets. It's the best way to be able to allow others see how you are doing and be able to best help you quickly with suggestions.
Spreadsheet setup instructions
Please click on the links for my spreadsheets for Shadoe and Oliver in my signature to see how I record my test results. As I am in Canada, I put both numbers in each box so that the people here who are in the US can follow, and also so I can give a copy to my vet so she can follow.
I think you may find that with the spreadsheet, a picture's worth a 1000 words.
Here is the portion of the protocol that is followed by most who are using Lantus/Levemir:
"General" Guidelines:
--- Hold the initial starting dose for 5 - 7 days (10 - 14 cycles) unless the numbers tell you otherwise. Kitties experiencing high flat curves or prone to ketones may want to increase the starting dose after 3 days (6 cycles).
--- Each subsequent dose is held for a minimum of 3 days (6 cycles) unless kitty earns a reduction (See: Reducing the dose...).
--- Adjustments to dose are based on nadirs with only some consideration given to preshot numbers.
Increasing the dose...
--- Hold the dose for 3 - 5 days (6 - 10 cycles) if nadirs are less than 200 before increasing the dose.
--- After 3 consecutive days (6 cycles)... if nadirs are greater than 200, but less than 300 increase the dose by 0.25 unit.
--- After 3 consecutive days (6 cycles)... if nadirs are greater than 300 increase the dose by 0.5 unit.
Reducing the dose...
--- If kitty drops below 40 (long term diabetic) or 50 (newly diagnosed diabetic) reduce the dose by 0.25 unit. If kitty has a history of not holding reductions well or if reductions are close together... sneak the dose down by shaving the dose rather than reducing by a full quarter unit. Alternatively, at each newly reduced dose... try to make sure kitty maintains numbers in the normal range for seven days before reducing the dose further.
--- If an attempted reduction fails, go right back up to the last good dose.
--- Try to go from 0.25u to 0.1u before stopping insulin completely.
Random Notes...
Because of the cumulative nature of Lantus and Levemir:
An early shot = a dose increase.
A late shot = a dose reduction.
A "cycle" refers to the period of time between shots. There are 2 cycles in one day when shooting twice a day.
Sometimes a dose will need to be "fine tuned" by adding some "fat" or "skinny-ing up" the dose.