Correcting high blood glucose levels

Page 25 of the DAFNE Manual states:
1 unit of quick-acting insulin lowers blood glucose by 2-3 mmol/l. For blood glucose levels above 11 mmol/l this rule does not necessarily apply.

One of my comments at the very start of the DAFNE course was that I found getting high (in the teens) blood glucose levels down once they were up was very difficult.
Now some weeks on from the DAFNE course and trying to quantify so much, I feel that the above Manual statement is spot-on; once I am above 11, 1 unit of insulin only reduces blood glucose by about 1 mmol/l.

The DAFNE doctor at the end of our course could give no scientific back up for the Manual statement. Is there some clear science behind it?

Hello, could it be something to do with glucose toxicity?

not heard of this.
are there not any doctors on this forum who could answer the question for us?!?

Hi, there are doctors/HCPs on the forum/site however you have to remember they are all very busy people so sometimes a response can take a while. The answer is there WILL be some clear science behind it since DAFNE is based on research both from the original in Germany and here, the research is still continuing. The question is can it be explained in simple terms ?

From my understanding, glucose toxicity means there is so much glucose stuck to the outside of the cells that it makes it tougher to shift it and normal rules no longer apply; it hits some kind of threshold where things go a bit woolly around the edges. So you need more insulin than you would imagine to get it all absorbed. This is, I understand, the reason for the need for so much insulin to be injected when you've got high sugars and ketones, which we learned about on the "sickness" part of the DAFNE course. I believe glucose toxicity can also mean your sugars can go up when exercising (if you don't have much insulin in your system already). So I might be wrong, but that may be the science behind the 11 mmol/l thing, it sounds logical to me.

Sorry, finally realised this is the Questions for HCPs thread. D'oh! You never know though - I could be right!

Actually, the correction factor for a high glucose is based on some experiments that the Germans did many years ago and depend upon whether the glucose level is stable, going up or down. If your glucose is on the rise the 1 unit may be insufficient where as if it is already falling then giving more than 2 units might be a problem and lead to hypoglycaemia. So 1 -2 units is a reasonably safe dose. However, these instructions are a guide and should give people confidence to experiment a bit more with their diabetes as they gain more experience and confidence. If you can face it then testing an hour or two later will tell you how this is going. The trouble is that a single glucose measurement can't give you this important information about whether glucose levels are stable, only repeated measurements can do this.
As for glucose toxicity, it really refers to the effect of a high glucose on the function of the pancreas and the fact that a high glucose an stop insulin being secreted by the pancreas. This is really only relevant to Type 1 diabetes at diagnosis and it explains why diabetes comes on so suddenly (the high glucose stops the insulin working which leads to a vicious spiral) and why when glucose is controlled, the pancreas had stopped working suddenly starts releasing insulin at least for a few days or months. Hope this makes sense.
Simon

Many thanks for these thoughts Simon. For the last 25 years I have always been bothered about responding to any one off bloods as you never know whether you are on the way up or on the way down. I frequently do repeated tests hourly when in doubt about what is going on. This is how I picked up the problem in the first place of 'getting stuck' in the teens and not being able to bring it down.
The German results make a lot of sense but in relation to my quoted observations, for the German info to explain them, I would have to assume that whevener I have a teens result, then I must be on the way up.

Thanks for clarifying this Simon. I've only ever heard about glucose toxicity from the DAFNE course at KCH, it was brought up because someone - possibly me because I'm terrified of hypos - queried why we had to inject such large doses of QA, and so often, when sick with high sugars and ketones present (our educators even drew a diagram of the cell with all the glucose stuck to it!). Would this be because the conditions when you're sick, with high sugars and ketones, kind of mimic the conditions at diagnosis?

Actually I think you have been misled about glucose toxicity. This refers as I mentioned to the 'poisoning' of the remaining cells which are still making insulin such that they stop working and produce this rapid onset of symptoms. What you are talking about is resistance to the glucose lowering effect of insulin due to the effect of your stress hormones which go up in illness and push your glucose up further. Ketones are a sign that these stress hormones are high and that there is not enough insulin in the body to overcome this. Under these conditions much more insulin is needed to bring glucose down. So not really glucose toxicity, it is more a high glucose due to the response to illness and stress hormones. Again I hope I have explained this clearly.