Rebecca,
I think I may have started the "confusion" issue with my reply earlier to Lori, and she and I probably should have had that conversation by PM rather than in the middle of your thread.
I'll try to remove the confusion if I can.
There are, when it comes down to it, two basic different ways that insulin works.
First, the type of insulin you are NOT using -
I'll call them "one shot insulins" - PZI, Prozinc, Humulin, Vetsulin would be some of the names of them. They can be short term or intermediate term insulins. They start taking effect an hour or so, maybe two hours after shooting. They tend to pretty aggressively counteract increases in blood glucose due to carb intake from eating, not too long after the food is digested and converted into glucose by the cat's system. They can last from 4-10 hours, depending on the specific type. And then once they "expire", there's no insulin from the shot still in the kitty's system. "Once it's done, it's gone" is a good way to think of it.
The other type of insulin would be Lantus like you are using, and another used a lot called Levemir. They are both "human" insulins which are also ideal for cats. They work very differently than the "one-shot" insulins. They are sometimes called "depot" type insulin. The way they work is that when you begin dosing with them, they build up a reserve (depot) in the kitty's body. Here we call it the "shed". After a few days, you have filled the shed with a supply of insulin. Gradually the cat will "withdraw" from the shed to attempt to lower blood glucose levels. When you shoot each 12 hours, you are "refilling" the shed. These "L" insulins enable you to basically always have insulin in the cat's system, 24 hours a day. The body will try to use enough to keep the BG down when it rises, and then you are the source of replenishing the supply so that it is there when kitty needs it.
Curves - With "one shot" insulin, the curve - which starts at shot time, goes low about 6 hours later ideally, and then ends at the next shot time 12 hours later, the ideal curve shape would look like a smile. Say you start at 300, go down to 150, and then back up to 300 in 12 hours. If you plot that on a graph, it would look like a nice smile.
With depot type insulin, the curve (If I say this wrong, some L user please correct me?) is usually a smaller smile. Not a flat line, but not a deep curve either. Because insulin is always present, the ideal thing would be for the insulin to keep the BG fairly even, with a little dip in the middle.
But with any insulin, there are curve shapes that can indicate that the dose is too high. If you see a flat line, and never any downward improvement in the numbers, that can indicate a dose that is either too high, or too low. Confusing enough for you? The other shape that catches your attention is one that is "inverse". I like to refer to it as a "frown", because that is what it looks like plotted on a graph. The BG actually goes up during the time when the insulin is supposed to be pushing it down, which is counter to logic. It usually indicates that some kind of "rebound" is going on due to excessive insulin. Kitty's body actually will fight the insulin, and release glucose into the bloodstream, resulting in higher BG readings.
With the numbers that you have been getting on tests, and the 1 unit dose you are shooting, there is very little reason to believe that 1 unit is too low of a dose. However, if you are seeing "flat" curves, it could indicate that the dose is actually too high. That is why Lori commented that she hopes your vet doesn't recommend a dose increase when they see those numbers. It is
very unlikely that an increase is needed with BG readings as low as you are getting at the pre-shot tests. I don't use Lantus, but I am almost certain that experienced lantus users would advise that the dose needs to be lower rather than higher. (really hoping one of them drops in and 2nds that).
Rising Number at shot time - It is very important, no matter which insulin you use, that the BG number is coming up when you administer a dose. If it is dropping and you shoot, the effect of the insulin would be greater than normal, and the BG can drop more than you expect. With numbers as low as you are dealing with, that can be risky if kitty goes really low.
So, when you test, if you don't see a number at shot time that is obviously higher than the last test you took, you need to hold off on shooting and feeding for 30 minutes or so. Then test again to see if you get a higher number. It is important that you do not give him any food while waiting, even if he insists it is time to eat! Food makes the BG rise, but it is supposed to do that. You don't want the rising number to be just the result of eating. We call that a "false high reading". You want the increase to be caused by the fact that he needs insulin, and his body will tell you that when you check his BG. This is what I meant when I remarked to Lori
"a "rising number" that was only rising from food"
When you got a higher number
8:14 am 153mg/dl. 2 hours post main feeding. 1unit of insulin.
that higher number was due to the food eaten 2 hours earlier. It was a "food boost" rise. Without food, it may not have gone up at all, and may even have dropped further. So with food in the equation, you can't be sure of the reason that the BG is going up. It's just a variable in the equation, and confuses things.
Well, hope that helps. And please everybody else, if I didn't get that right, please correct me. This dance is hard enough to learn for newer members without me or anyone else throwing incorrect information at them!
Carl in SC
