are the effects of insulin linear?

Last night, Melville's PMPS was 430. I gave him 2 units of Prozinc. Four hours later, he was at 161. That's a drop of 269.

Now, let's say, hypothetically, he's at 250, which is generally considered to be a safe "shoot number." I assume that I shouldn't expect him to drop to -19 after four hours, so the effects of insulin clearly aren't linear. But what accounts for the difference? Is it that he eats enough just before getting a shot that his glucose is effectively +200? Or is there some other mechanism in place?

Thanks!

 

Unfortunately just not that cut and dried. We have a saying that applies to almost everything having to do with diabetic cats: every cat is different. And the insulin acts differently in every cat.

The best way to figure this out is to collect the data. Once you have some numbers that suggest with a 300 preshot (for example) and 2 units, he had a nadir of 160, then you can figure the next 300 preshot, the same dose might have similar effects. If you want to try for a lower preshot and lower nadir, then you might think about a dose increase of .25 units. You try that and see if both preshot and nadir were lower.

The data will also help you figure out if your cat has a rise right after the shot - often due to food boost. It can tell you if he is a cat that takes a few days to settle into a new dose or if he reacts with the first shoot of a new dose.

 

The important thing to keep in mind that is on a preshot of 250, if 2u pushed him down today 269 points, it could do that no matter what the preshot number is, so naturally, you'd shoot much less insulin on a lower preshot. That's what is so helpful with collecting data like Sue mentioned. And that's why testing before every single shot is a must. You have to be sure the number justifies the dose.

Unfortunately, the results are linear or even repeated in many cases. The same dose the next time you get a 400+ might not do as much, or might do even more. There are so many variables....how much he eats, what the carb content of the food is, how he's feeling that day, how much his liver reacts, how much his pancreas helps, how active or non-active he is during the day. All of this effects BG numbers.

The best way to approach the routine is to start at a low dose (usually one unit BID) and collect data until you figure out what that dose will do to his BG. Also try to keep the food and carbs as constant as possible. The more "constants" you have, the easier it is to account for the "variables", if that makes sense....
Carl

 

The problem with trying to look for a linear effect is that the insulin is not going into something like a machine that would not alter the output in any other manner. It is going into a cat, where there are many other mechanisms within the cat that are also working to affect that BG number.

Insulins are also not all the same. Lantus is not even dosed on preshot numbers. In theory it doesn't matter what you see preshot, you adjust your dose based on nadir numbers not preshot numbers.

You also don't adjust at every shot, but allow a dose to settle even though you will see movement in the numbers. Unless you see dangerously high or dangerously low numbers, you don't react to preshot numbers with a dose change. That lends itself to say that the effects are not linear or we would be adjust the dose every time we tested preshot.

 

I need an editor!

Obviously, I misquoted myself...

should have read "the results are NOT linear.."

oops,
Carl

 

blodd glucose is multifactorial and includes glucose level, insulin dose, digestion, protein/fat/carbohydrate content of food, activity level, comorbid illness, other hormones, ....

So no, it is most definitely not a linear relationship.

You try to control the factors you can, so you can reach a stable dose.

 

bjm had a very good point - we try to control everything possible so that the only variable is the dose. i feed my cat the same food, at the same times of day, same amounts, basically same treats, so that as much as possible he is stable. then i adjust his insulin.

also, insulin is a hormone. think 13 year old girls - tears one moment, happy the next. it isn't like the med i take for my high blood pressure that's been the same dose for a couple of years.

cats, dogs and people all get diabetes - and between the three, cats are the very hardest to regulate. people can get insulin shots once a day, dogs can stay on the same dose for a long period of time, but cats are so unpredictable. another reason to hometest.