As long as you keep your vial of ProZinc refrigerated, it
should remain potent for about 6 months; I have even pushed mine to 7 months.
Could be any number of factors/ changes you've made along the way. But as you only just started home-testing, it's all guesswork until you are testing consistently at AMPS/ PMPS time, as well as some tests around the time frame of when cats usually nadir (roughly between about +4 and +6/+7 hrs. after the shot.
I am glad you intend to home-test on a regular basis from now on -
this really is essential, not only to make certain you're keeping Mr. Black safe, but also so that you can look at those numbers in a spreadsheet and SEE his pattern. As mentioned earlier, this will provide you with a
much clearer picture of how Mr. Black is processing the insulin. And based on the numbers that we can see, it will make it easier to determine how/ when/ how much to adjust his doses of insulin. Having seen what can happen when a cat gets too much insulin injected into his body, I am more than a bit concerned about your vet's current assessment of Mr. Black's insulin needs. A 135 BG reading on lab equipment is a pretty low number. So was that 75 that you reported you got on your Relion meter. (I don't think that was any type of meter "error.") But I don't think just going "cold turkey" on the insulin at this moment in time is a wise idea either. You could end up losing all the ground you've gained - and with nothing but the in-clinic BG#s to go by (up to this point where you're finally home-testing), we would only be guessing about his overall history since we don't have enough data yet.
What time will you be doing his next pre-shot BG test? PLEASE post that number on a new thread with a title that reads something like: "Need Dosing Advice ASAP." Depending on the number you get, you may want to reduce the amount of insulin. You do not want to shoot insulin if that number is too low. I would recommend that you read through this doc now, before your next pre-shot test time:
Protocol for ProZinc/PZI
(It's the same one that
@Elizabeth and Bertie sent you earlier.)
It disturbs me that your vet wasn't having you home test. Please look at it this way: If your Mr. Black were a human child, would you shoot him with insulin without
first checking his blood glucose level? Of course you wouldn't! Nor would your child's doctor tell you it was okay to skip that essential step! So why some veterinarians think it's "ok" to skip the pre-shot BG tests that would keep our cats safe is beyond my comprehension ...
Bottom line here is: You're probably going to end up knowing more about treating feline diabetes than your current vet does. (Just sayin.'

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