Can someone explain how one insulin pen says 100 units/ml and another insulin pen says 200 units/ml? Yes, on one hand, I understand the latter pen contains more volume. However, a unit IS a unit, correct? A “unit” is a standard measure so, the units/ml should be a constant value…right? It’s late at night after a long day…am I missing something obvious here?
Nm, I decided your pens may be different than mine, don’t want to steer you wrong. Call the pharmacist in the morning.
The only logical explanation I can is that this “system” of measure is trying to express a concentration. How else can there be 100 units/ml AND
200 units/ml? I was misinformed, I wager, thinking a “unit of insulin” is simply a measure smaller than a ml. Very confusing! And, it can be quite serious if not properly understood! Perhaps someone can come along and validate my thinking.
Yes, I surely will! Very confusing system of measure when it should be so logical, right?
Units/mL are a measure of concentration. How a “unit” is defined differs from substance to substance. In a biology lab, enzymes are often packaged in various units/mL concentrations and the unit is defined something like “an amount that can cleave a certain number of DNA molecules in an hour.” According to some site I just found the unit definition for insulin is “One unit of insulin is defined as the amount of insulin that will lower the blood glucose of a healthy 2 kg (4.4 lb) rabbit that has fasted for 24 hours to 2.5 mmol/l (45 mg/dl) within 5 hours.”
Definitely call your pharmacist.
Jinx, you have opened a can of worms.
You are correct. Units/ml is the concentration of insulin within a given volume. Concentrations have varied since the discovery of insulin. Some countries commonly used concentrations ranging from 10 units/ml to 500 units/ml. This led to frequent mistakes resulting in under or overdosing. This was sometimes fatal. An effort was made to limit concentrations available to consumers. In the US, insulin for consumer use has almost exclusively been available in 100 units/ml (U-100) for many years, (500 units/ml has been available for hospitals and some high use patients). A 2007 paper in an Indian medical journal mentions that the WHO recommended that all countries adopt the U-100 standard.
Several things have changed this trend towards standardization. Many patients are using such high amounts of insulin that they can’t reasonably inject that much volume subcutaneously. Also recent research has shown that insulin can be more or less effective depending on the concentration. Lastly, devices made to aid consumers with injecting can only hold so much volume, so more concentrated solutions are easier to package.
U-200, U-300, and U-500 concentrations are now available or proposed in the US.
None of this even touches on the different types of available insulin.
Yes , you want to inject UNITS and not volume.
Sorry, that last sentence should have read “You want to inject the correct amount of units and not volume”.
I would be interested in what kind of literature came with the U-200 pen.
It is logical! The amount of insulin each person with diabetes needs is measured in “units” - **Shagunathor **has said how this is defined! So for a daily basal dose this might be - say - 15 units or for an injection of a short acting insulin before a meal - say - 1 unit for each 10g of carbohydrate they are about to eat. The point of an insulin pen is to make this very simple - you just dial up the number of units you need on the pen. You don’t need to know the concentration, the pen is set up to work with a particular type of insulin of a particular concentration.
The reason of course for having the 200 units/ml (and I believe 300 units/ml) strength insulins is that some people need to take a lot of units in one go and the high concentration forms reduce the size of the injection.
As with everyone else has said, speak to your doctor/pharmacist if you are in doubt about what you should be taking but the general point is simple enough.
Very interesting to read all the replies. Thanks everyone for your input. It has been very enlightening to follow the logic once I understand that U-100 or U-200 is a concentration.
I’m not diabetic, but to me this seems to clearly indicate that the 200 units/mL pen is twice as concentrated as the 100 units/mL pen. In other words, a 1 mL dosage on the 200 units mL pen would be equal to a 2 mL dosage on the 100 units mL pen. Is this not the case?
Your facts are right but your truth is mistaken. The truth is, you do not mess with mL. You stay away from second-guessing, because it’s dangerous. You think in units and pay no attention to the rest. It may sound silly, but the truth is (and nothing to do with anyone here), a stupid person needs his insulin just like any other diabetic, and so the system must by default accommodate a stupid person.
I hadn’t realized until this thread that a “unit” is not a measurement of volume.
Ignorance fought…Thanks!