[Geoff]

This is a bit of general info I came across today.

Insulin is measured in units, abbreviated U
(international units, previously abbreviated IU).
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

Not a lot of people know that!

[HelenM]

Poor rabbit, first you starve it, then you give it a hypo!

[ant hill]

You have got it right there Helen, Poor little rabbit.

[Stuboy]

lol Poor little wabbit!

[xMenace]

Is that an African or European a rabbit?

[BriOnH]

Where did that 'definition' come from? It has to be one of the worst definitions I have read.

[Moreno]

Silly rabbit. Why you let those mean jeans human being get you!

But anyways I never knew this so far.

[Geoff]

Hi Brian, the quote is from the following book.

Type 1 Diabetes
in Children, Adolescents, & Young Adults
( How to become an expert on your own diabetes)
By Dr Ragnar Hanas, MD, Phd Consultant Paediatrician.

If you want to read it yourself, pm me and I will send you a copy.

[Real4]

Originally Posted by BriOnH

Where did that 'definition' come from? It has to be one of the worst definitions I have read.

Why is that a bad definition? It is a functional definition for calibrating an insulin dose. You need a single measure so that all forms and types of insulin can have the same meaning - in terms of the insulin's physiological effects on the body.

[JediSurfer]

why was a rabbit used. doesnt make any sense. surely a diabetic adult human would be far more effective.

[BlueSky]

Originally Posted by JediSurfer

why was a rabbit used. doesnt make any sense. surely a diabetic adult human would be far more effective.

The problem with adult humans is that they are all so different. They have varying insulin requirements and levels of insulin sensitivity. Rabbits are pretty much all the same. Humans also don't like being used as guinea-pigs (or rabbits) for scientific experiments.

Google brings up the following definition for a unit of insulin :

The activity contained in 1/22 milligram of the international standard of zinc-insulin crystals.

... but I guess that quantification must have been arrived at by relating it to some level of effect.

[fgummett]

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

Interesting but unless all healthy 2 kg wabbits have the same fasting blood glucose isn't this definition missing the starting blood glucose

[Geoff]

Hi Frank, I think you are missing the point here. It's a healthy none diabetic rabbit, just like if you tested on a healthy none diabetic person, their normal bg would be around 4.8mmol/lt (86)
by fasting for 24hrs there would be no additional effect from diet,

Ask one of your none diabetic friends to fast for 24hrs, test their bg before and after and see how much variation there is.

The only thing is I don't know what a healthy rabbits bg should be?

[fgummett]

Hey Geoff... I understood that the normal range for an adult human fasting blood glucose is a range rather than an absolute value... in that case it follows that it would require a range of insulin amounts to reduce that range of values to a fixed value..?

[HelenM]

A bit of googling found this:
the Nobel prize lecture by Banting 1925

The method of estimating the potency of Insulin solutions is based on the effect that Insulin produces upon the blood sugar of normal animals. Rabbits serve as the test animal. They are starved for twenty four hours before the administration of Insulin. Their weight should be approximately 2 kg. Insulin is distributed in strengths of 10, 20, 40 and 80 units per c.c. The unit is one third of the amount of material required to lower the blood sugar of a 2 kg. rabbit which has fasted twenty four hours from the normal level (0.118 percent) to 0.045 percent over a period of five hours. In a moderately severe case of diabetes one unit causes about 2.5 grammes of carbohydrate to be utilized. In earlier and milder cases, as a rule, one unit has a greater effect, accounting for three to five grammes of carbohydrate

http://www.discoveryofinsulin.com/FGBLecture.htm][/

I found that the rabbit method of assaying insulin was used until recently, when animal insulins were used there could be variations in potency. Today,chromatography is usually used. However the test is still done (at least I found a firm who specialised in this type of testing and the US pharmocopeia gives instructions for the procedure.

A British test used mice

To determine the
potency of unmodified insulin the test is to inject two groups of mice, one with insulin of a known strength (standardised by reference to the international standard preparation), the other with the insulin under test. A comparison of the incidence of hypoglycaemic convulsions in the two groups shows the strength of the sample vis-a-vis the standard.

This report is interesting as it describes how animal insulins were produced