Cat's BG is dropping in AM rising at PM

[Jessica Taddei]

I originally posted this in the glargine forum. Maybe this is a more appropriate spot!
Hello! I am new here and read through all of the sticky posts but it was a lot of information so please forgive me if I sound confused
I wrote out a huge post but it seemed like so much information, I can give more info if needed. Long story short my cat Stinker is 6 years old and was diagnosed as diabetic in January. We have gone through several foods and amounts of insulin and he is driving me nuts!

Currently he is on 3 units of glargine, we draw it up in a syringe
He is eating young again zero food our other cat is also eating this and they do not get treats
His insulin is always SO high (400-450) curves were showing his numbers not really creating a bell but more going 450-390-430-380-415, etc. over a period of 12 hours.
Two days ago his AMPS was 158, I didn't know what to do so I skipped his dose, that night it was 400. Called my vet the next day and she said give him 2 units if it is between 100-200 and to skip if it is under 100. This morning it was 88 so I skipped his dose again. We use the alpha trak 2 to capture his BG.
Someone please help explain to me what is going on because I am confused

 

[Larry and Kitties]

Sounds like 3 units was too high. When too high you typically get a relatively flat curve like you wee seeing. Not going to too low of a BG is due to the liver dumping glycogen in the bloodstream to maintain a high enough BG. This can only go on so and after a while on too high of a dose BG will go low like you recently saw.
Glargine/Lantus is a depot insulin and thus it works best when the dose is constant and not variable like you vet proposed.
I myself do reduce dose somewhat when I get a too-low preshot instead skipping the dose in order to help maintain the depot.