Volume isn't the same of insulin "activity". Remember the old days of U-40? U-100 is 250% as potent for the same volume. And U-500 (which is available today) is 1200% as potent as the same volume of U-40.
As far as I can figure out... the definition of insulin activity is still the good old rabbit unit!
Tim,
Yes, correct. I meant to say the volume of U-100 units are the same (or U-40 units, etc.)
OK, did some googling, and found a nice summary written almost 90 years ago. I think in my first response I was referring to the "Banting and Best rabbit method" where they actually measure the bg of the rabbit. The Eli Lilly method of testing for a unit of potency, was a little more primitive: if 75% of the rabbits were having convulsions from hypos, it was a unit!!!! No wonder they needed so many rabbits!!! The Rabbit Method of Standardizing Insulin
A unit is a unit, but the effect of different types of insulin is different not only because their different time actions.
Not all the insulin you inject is used by your body.
Some never reaches blood, so it's used locally by derma cells and then destroyed.
The main part reaches blood, then it travels through your body cells and is used and reused (insulin is an hormone, it links and de-link many times from different cells before ceasing its activity) to process glucose, then destroyed by liver and kidneys.
How long is insulin in blood used ? Insulin of a healthy pancreas acts only for few minutes in the blood then it's discarded.
Injected insulin goes into blood slowly through skin and reaches blood through capillary vessels, so it could get discarded earlier.
If you give yourself a big bolus it's different then injecting the same units over a longer period, because (among other things) when you have more insulin in your blood it gets disposed earlier by you body.
Here is an intersting article (link)
Hope this helps.
My understanding is that 1 unit would represent a constant number of insulin 'molecules', when measured scientifically. Depending on the type of insulin, the molecules are chained together, and the chains are not usable. So that's where the time factor comes in. Over time, the 'chains' are broken down, until eventually the individual insulin molecule is 'free' and can be used.
BUT, during the time frame that the chains are breaking down, there are many factors that can influence your body's insulin resistance, or better thought of as insulin 'receptiveness'. To me, this means how much 'glucose' does each molecule of insulin move out of the blood.
So maybe there are 10 insulin molecules, and you are exercising. That might reduce your BG the same as 15 molecules when at rest, because your cells might be more 'receptive' when exercising. Or when your BG is high (or stressed), 10 molecules seems to act more like 5. And if your liver is dumping glucose at the same time, or you are digesting food, maybe an increase or no change in BG at all !
So maybe the answer is Yes in 'scientific' terms, and No in terms of effect on BG on an hourly basis - because the 'chains' are not breaking down at the same rate, even if all other factors were 'equal'.
Maybe this site will help. insulin structure
and this link (from same site) that has a cool simulation of glucose going into cells. glucose uptake
Very nice scientific explanation of why what we know is true is true!
Uproden..this insulin thing is still VERY new to you. I see where you were diagnosed just in December 2011. Admirable job in getting your a1c to 6.2.
:+)
Levemir/Lantus are not used to correct high blood sugars nor to "cover" food intake.. Their purpose is to maintain blood sugar at a normal range for a long duration of time, over 20 hours.Novolog is used to correct high blood glucoses and to "cover" food intake with enough potency ( number of units)to keep blood glucoses in an acceptable range after food consumption.Novolog and Humalog last(work on blood glusoses)in most people for around 3 hours. As many posters have said you cannot compare the action of the 2 insulins without considering the time. The unit, the volume, is the same unit, but the duration and the time of action are not the same.You cannot take time out of the explanation..
Suggestions:Read nthe books Think like a Pancreas and Using Insulin for thorough explanations of how insulins work.
You will get used to the variablity of life with type one diabetes.. Really, sweetie, YOU WILL.
God bless,
Brunetta
Type one 43 years
When we used U-40, we had to use syringes designed for U-40 insulin. During the transition to U-100, there was a lot of emphasis to make sure you used the right syringes for the insulin, or you would get an incorrect dose.
I think I understand what you're asking, but I would not think it would be the same at all. Yes it is the same technical amount of insulin that should do the same technical job, but because it is formulated differently, it has a slower onset and lasts longer..
So I guess if you wanted to set up a study to look at this, you'd want two completely separate days separated by a certain amount of time to try and normalize results. If your TDD was 24u, you'd take 1 unit of Humalog every hour, on the hour, for 24 hours. Then you would go back to a normal regime for a few weeks to get regulated properly again and then do 1 unit of Lantus/Levemir every hour, on the hour, for 24 hours. It would probably also be better if you were fasted for those 24 hours so you don't have food confounding the results. You'd probably have to test your BG at least every hour to see how it is responding to your repeated administrations. You'd have to eat similarly and maintain the same exercise level too.
But eh- a unit is a unit is a unit is a unit, at least as far as these two types of insulins go. I do not believe they are going to do the same thing to your blood glucose, mostly because they peak in a very different manner and the sharper that peak, the more your BG will drop...
Kinda see that with antibiotics... short acting penicillins are pretty much like BAM- hit the system with one hard pop and then they kinda pitter out. You're trying to achieve a certain concentration in the bloodstream in this case; and you DO achieve it, it's just more of a hard hitter all at once...
With long acting penicillins they take a little bit longer to build up in the system (they don't go BAM!)... BUT they do reach the level required in the bloodstream for killing infection or whatever else is going on. And after that, it will stay at that concentration for a longer period of time...
Anyway... that's what I think about it... hope you find your answer.
Lots of good information here I really appreciate everyone's participation. I want to clarify one thing though my question has nothing to do with my treatment, it is hypothetical and stems soley from my insatiable curiosity about.... well everything.. Whoever said a unit is a unit by volume is dead on the money of course but I am more interested in the effect.
I thought of another way of explaining my question while maintaining time as a factor as it seems to be a sticking point.. I have a good friend who is on a pain killer. The effects of the pain killer were spiking too high and not lasting long enough to help him so they switched him to the "ER" (extended release) version of the same pain killer and it is working for him.
He says the effects of the ER and non-ER versions are exactly the same but the ER version has no spike and lasts longer. As I understand it, they are the exact same medication its just that the "delivery rate" of the ER version is somehow modified.
So in terms of insulin, is levimir the ER version of novolog? or are they two different drugs with other properties (other than time) that are different as well?
On a personal note, my last a1c was 5.5, I am very very "lucky" to have some close friends and family members who are type 1's and have helped me greatly in this process.
The answer lies with Megaminx's reply up above.
While there are relatively slightly different structural difference between the insulin molecules of one type and another they are also sufficiently the same so that one insulin in theory is the same as another. In practice however there are differences from one individual to the next as well within one person.
Minx talks about insulin being delivered in the body as chains in which the individual moluclues of insulin are inactive as long they are chained together. In Levemir for example, these chains of insulin become attached to the albumin in our bodies right after injection. Over a period of time (hopefully 24 hours) these chains slowly release indvidual molecules of insulin as they dissaccociate from the albumin. Lantus works in a different manner. Lantus is "in solution" at an acidic level and upon injection this acid is neutralized to the PH of our bodies. The Lantus then crystalizes out of solution into chains in the neutral PH of our bodies whereby the indivdual molecules are held inactive. Again, slowly . . over ideally 24 hours the individual molecules of insulin are released becoming active in the process. In practice this can vary from one person to the next.
While I don't have the exact process involved for the fast acting insulins, I this process happens on a much faster scale. The second part of your question is that essentially yes, the insulins in theory are all the same, but they've been altered in such a fashion as to insure different rates of how long they take to release. Once again this can vary from one person to the next.
ER types of meds such as what your friend took and others I would believe, do so by binding up the effective drug with other chemicals that would slow down the absorbtion of the desired drug as opposed to actually changing the chemical structure of the drug itself.
Another review article on measuring insulin potency and defining the unit, this one from 1960. They show more ways of measuring insulin potency, still using the effect on a rabbit as the definition: Methods of Insulin Assay
Kiva's explanation explains the long acting versions perfectly and in detail..
A unit is a unit is a unit. Long acting and short acting insulins both have, ultimately, the same job in the body. Long acting insulins act longer because they release slowly over a longer period of time (to put it in your words: the "delivery rate" has been altered).
Sometimes when drugs are put into 'extended release' formulations (as I talked about with penicillins earlier in the thread), you may see different side effects. This would be more likely due to whatever the manufacturer has added to help make the drug release over a longer period of time. Depends on the drug, but some of them are oil based... sometimes, in the case of radioactive 'seed' implants or antibiotic beads, an actual physical object is implanted that has been impregnated with the drug, and the object releases the drug over time..
If you want to read more about the different ways they turn things into 'extended release' formulations, google 'long acting drug formulations' or something similar.
This is from the 1960s, there has been some significant progress in the last 50 years. Today we have moved to performing chemical assays of insulin and I don't believe the hypo rabbits are used much anymore.
Hypo Rabbit is a great band name!
And you play in it, Acid(LOL)?
God Bless,
Brunetta
That is true, I don't think they use the rabbit method regularly anymore, but the base definition of the chemical assay method was done to be compatible with the original definition of the HYPO RABBITS.
A unit is a unit by volume - is only true when you are comparing insulins that are the same 'potency', such as U-100, which is the case with most insulins in US today.
U-100 was formulated so that it is always 100 units / ml.
I think U-40 and U-80 might still be available outside of US - 40 and 80 units/ml. U-500 is also used in rare cases.
But as long as the right 'syringe' is used to get the right 'volume', then a unit is a unit is a unit, within the respective amount of volume.
Don't anger the hypo bunnies!
Kiva this is EXACTLY what I was looking for thank you so much!!! Now on to the rabbits… Lol