Here is the link to your last post here, for continuity:
Leo August 31
If you are keeping insulin in the fridge, vial or pens, it should last much longer. Pens typically go to the last drop, vials I've seen people use for 5-6 months.
Your problem is that he is on two high a dose. When a cat goes under 50, the dose should be reduced by 0.25 units. He got to 49 both on the 7th and 9th of September. His dose should be 2.5 units.
Both on the 5th and yesterday, I see a note of probably fur shots. When you think that happened, could you put FS beside the unit number. So for last night, it should look like 3FS. That tells us easily that there was a fur shots. Fur shots deplete the depot and you'll see higher numbers for a few cycles after that.