Insulin Levels?

[JediSurfer]

Why do we still not have a way to test how much insulin is active in our bodies?

[cheryl]

There is it is a c-peptide test......I had one a year ago,

Cheryl

[JediSurfer]

I mean more like a blood glucose tester which we use day to day.

[JediSkipdogg]

The C-Peptide is currently the only way to determine what the body produces. There are no tests to measure straight insulin level though as there would be no need and the test result would vary hugely from person to person.

Although, the C-Peptide test itself is heavily disputed at times due to the nature of the test. Firstly, C-Peptide is produced in the body at a 1:1 ratio with insulin. The problem though is Insulin is processed and eliminted in the liver with a half life of 5 minutes. C-Peptide is removed by the kidneys with a half-life of about 30 minutes. Therefore, it's hard to ever say if a C-Peptide can truely match insulin levels unless during a fasting period and then that puts approximately 5 times as much C-Peptide in the bloodstream as Insulin.

[BlueSky]

The C-Peptide is currently the only way to determine what the body produces. There are no tests to measure straight insulin level though as there would be no need and the test result would vary hugely from person to person.....
Insulin levels can be tested. See here for details Insulin: The Test (http://www.labtestsonline.org/understanding/analytes/insulin/test.html) The main cause of variability in fasting levels is insulin resistance. A fasting level of 5-20 mcU/mL is considered normal but people with metabolic syndrome or T2 will often have fasting insulin levels of 90+. Insulin levels are a good indicator of how well insulin resistance is being treated,but it doesn't get tested normally because there is no drug out there that reduces insulin levels.

[JediSkipdogg]

Insulin levels can be tested. See here for details Insulin: The Test (http://www.labtestsonline.org/understanding/analytes/insulin/test.html) The main cause of variability in fasting levels is insulin resistance. A fasting level of 5-20 mcU/mL is considered normal but people with metabolic syndrome or T2 will often have fasting insulin levels of 90+. Insulin levels are a good indicator of how well insulin resistance is being treated,but it doesn't get tested normally because there is no drug out there that reduces insulin levels.

I meant to say no test that detects body insulin only. Our injections of insulin would mess with that as far as I can tell. I haven't seen anything that says any insulin test would not also detect injected man-made insulin.

[Funnygrl]

Jedi- what do you mean when you say that fasting you have 5x more c-peptide in your blood? I'm having a c-peptide test, fasting, soon and want it to be as low as possible, honestly.

[JediSurfer]

I would just find it useful to beable to test to see if all the insulin I have injected is still active. I doubt this will ever happen. So I will be quiet.

[JediSkipdogg]

Jedi- what do you mean when you say that fasting you have 5x more c-peptide in your blood? I'm having a c-peptide test, fasting, soon and want it to be as low as possible, honestly.

It lives approximately 5 times longer than insulin, therefore there's always going to be more C-Peptide than insulin. Labs know that information and base their scales off of it. However, one interesting thing I found is there is no national reference range for a C-Peptide. Labs have to come up with what range they want to be acceptable for how little insulin one produces. So if you had it done the first time in a different lab, this result may be the same or different than your first test.

[xMenace]

I would just find it useful to beable to test to see if all the insulin I have injected is still active. I doubt this will ever happen. So I will be quiet.


That's ok. I'm following you. It would be a very handy thing to know. The problem as I see it is not all the injected insulin gets into the bloodstream immediately. It can take a long time to be absorbed. You'd have to account for that little blob floating around in that fat-pocket.

[tanyatype1]

That's one thing that I like about the pump JediSurfer - it has an insulin on board feature. It keeps track of how much of your bolus is still active, and how much has already been used up. (you probably already know this!)

[Gary_W]

I'd like this idea and I wish my fingerprick tests would come out with BG reading AND insulin left, but I can't see how it could work though this could be me misundertanding how the insulin shots are absorbed.

My current undertanding is that certain substances are added to the insulin vial that slow down the insulin's release. In the case of Lantus, that's what makes it last 24 hours (*cough*). As such, if an 'insulin on board' finger prick were available would the test actually 'see' it as insulin until it has broken free of the additive / got out of the subcutaneous layer into the blood stream / whatever on earth it does? Excuse my usual birds eye view of the subject but I recon the 'slowing down' additives would make the test not work. Any thoughts folks?

Tanya - I like the sound of that insulin on board bit of the pump. I didn't realise they did that, but as the UK seems to have its nose pressed to the outside of a frosted window, looking through to the pumping frenzy going on across the pond I probably don't find out as much as I should. I must admit I don't like the thought of being permanently plumbed in to something, though features like this do make me want to take a serious look.

Having said that, the pumps available in the UK would not have this feature. They would be clockwork (to save on the batteries) and would speak about the weather with each bolus dose. Those are features us Brits can relate to that would bring out our crooked little smiles. Especially if it can toast a crumpet in under 3 mins in the event of a hypo.

Gary

[JJM335]

Some info on Insulin release rates:

In the olden days we had animal insulins. You had to grind up a piggy's pancreas and purify the insulin; this gave you Regular/Actrapid. The problem with injected Regular insulin is that it is absorbed from the injection site over a period of about 5 or 6 hours. To slow down it's absorption, either Zinc (Lente), or Zinc + a protein from salmon sperm (NPH) were added. This made the insulin insoluble and slowed down its rate of absorption, increasing its time of action.

The first generation of human insulins were made in genetically engineering bacteria, but like their animal predecessors, were available either in soluble or insoluble form. However, genetic engineering allows the modification of the insulin protein chains to make new forms that don't exist in nature. The objective with all of the analog insulins has been to make small modifications that alter the rate at which the insulin is taken up from the injection site, but at the same time leaving the interaction with the insulin receptor (i.e. the "working part") unchanged.

Humalog, Novorapid (AKA Novolog) and Apidra have all been modified to speed up absorption. This is a fundamental change in the protein, not an additive. Lantus and Levemir/Detemir have been modified to slow down absorption.

In the case of Lantus the insulin molecule has been modified so that it is soluble at pH4 (acid) but insoluble at pH7 (neutral). It is supplied at pH4, when it hits the neutral pH of the body, it becomes insoluble and that slows down the rate at which it can get into the bloodstream. Levemir/Detemir uses a different approach. A fatty acid molecule has been added to the protein (again by genetic engineering). This makes is stick to cells and keeps it from entering the bloodstream too quickly.

The problem with measuring "insulin on board" is that much of the insulin is sitting at the site of injection, slowly entering the bloodstream. With MDI, it's hard to envisage a method that could measure how much is there. It should be easier with a pump, where the insulin reservoir is in the pump, and not sitting under the fat layer somewhere in your rear end.

Joel

BTW I should imagine that a UK pump would run on coal rather than clockwork, and would be attached to a dedicated Sinclair ZX81 which would work out the Bolus for a Fish Supper or a Takeaway Curry.

[dazzy34]

you would need to be trained and certified to use a UK pump for health and safety reasons and wear a hardhat and gloves. the pump would have to be luminous green and waterproof in case the rain gets in it and blows you up.

[dazzy34]

Its probably safer just to go into hospital where you will most certainly die of a superbug.

[xMenace]

It should be easier with a pump, where the insulin reservoir is in the pump, and not sitting under the fat layer somewhere in your rear end.


No, you still have injected insulin. The insulin in the reservoir is analagous to insulin still in a pen or vial.


I would hope UK pumps would be able to take our a Dalek or two http://www.agr-s.com/forums/style_emoticons/default/2gun.gif

[BlueSky]

... I like the sound of that insulin on board bit of the pump. ....
To me, this feature was very disappointing. A very simple algorithm is used to do the calculation and I found my intuitive judgement to be much more reliable. I would normally have to overide the pump, which adjusted correction boluses downward because of insulin-on-board. I also found the correction factor and insulin:carb ratio to be problematic. I find these co-efficients to be highly variable, and pump software treats them as constants. To me, this is not realistic. There are simply too many un-measurable variables involved.

[Gary_W]

Joel - Thanks for explaining this. It really clarifies something that I barely understood (as you could probably tell :) )

BlueSky - That's a shame. Can you not plumb in the algorithms for different times of day? I was under the impression that some pumps out there were pretty customisable but it's another huge gap in my knowledge.

Gary

[tanyatype1]

Personally, I like the insulin on board and the EZBG feature. The calculation can change (with the ezBG feature) for different times of the day depending on your ISF. (insulin sensitivity factor) I'm more sensitive to insulin in the AM and late at night, than I am at dinnertime for example. When I'm using the ezBG feature, I just have to remember to adjust my ISF if needed. With the carbsmart feature, you can also adjust the calculation by changing your I:C ratio. (insulin to carb ratio) The pump isn't perfection though. I still take into account, things that the pump cannot, like if my meal was high fat, (longer time to digest) or if I'm planning on going for a run. There are things that we still have to think about ~ the pump can't do it all, LOL!