View Full Version : Duration of insulin and what the numbers mean, or don't

11-20-2012, 03:45 PM
I am going to post an image of a sample curve - part of the curve is a miscellaneous choice of readings but the first ones are Sissy's readings posted yesterday for the morning.

In this curve, the insulin has good duration, which is defined as the blood sugar returning to a level no higher than it started out. So if the blood sugar starts at 381 as Sissy's did yesterday, the NPH has a good 12 hours of duration as long as the blood sugar is basically the same or less at dinner time. In this case, hers was 306, so she might actually have had some insulin action from her breakfast injection still working at dinner time.

It's somewhat counterintuitive... it's not that the blood sugar should never go up during 12 hours, it's a matter of how much it goes up and relative to where it started.

So if there's an off day and blood sugar starts at 600, you can't expect the same dose of insulin to bring that blood sugar to the usual 300 by dinner time.


11-20-2012, 03:49 PM
It's also important to remember that meters are not highly accurate instruments. More than accurate enough to be useful, but not so accurate that there is any meaningful difference in readings of 394, 402, and 380.

Managing blood sugar is all about the "big picture" - trends over time, patterns, and meaningfully large changes in blood sugar.

Sissy's numbers from yesterday in the morning are a dog who needs more insulin. It's fairly flat with some of the readings being completely steady realistically. So no need at this moment to correct food or insulin based on these numbers.

That may change as the dose goes up, and it may very well be that Sissy's response varies from day to day. That's pretty common.

Which is when you get back to focusing on the big picture... what does she do most days? An out of the blue blip one day isn't cause for concern. They happen, to every dog. When it becomes a trend, a pattern, then it's something to worry about.


11-20-2012, 03:58 PM
I didn't post this earlier because it's an atypical curve that shows what was likely either a rebound or an intervention with glucose by the vet in response to a low. But it demonstrates what is considered to be the duration and nadir of blood sugar, backing up the definition I have been using.

This is from the NAVC's Clinician's Brief article by Thomas Schimmerhorn at Kansas State University.


So please note that in this curve a low blood sugar event occurred and glucose was likely added to the bloodstream, either as a rebound by the dog's body or by veterinary intervention.

It's also important to remember the discussion in the Clinician's Brief article that blood sugar at any one moment is a combination of multiple factors:

Serum glucose, at any single time point during the GC, represents the sum effects in the rate of:

- Exogenous insulin absorption - how the injected insulin is absorbed

- Intracellular uptake of exogenous and endogenous insulin

- Insulin degradation and elimination

- Intestinal glucose absorption

- Endogenous glucose production
(glucose released from stores in the body by the liver)

- Tissue glucose uptake and utilization

Another reason to stick with the big picture! ;)