Insulin syringes

Not looking for medical advice; this is just something that came up in conversation.

I know that different syringes have different capacities, but does the word “unit” represent an actual amount, regardless of the type of syringe? If I inject myself with 50 units of insulin from syringe A, and you inject yourself with 50 units of insulin from syringe B, are we both getting the same amount?

And here’s a more detailed question: Is taking 50 units of U-100 insulin with a U-100 syringe the same as taking 10 units of U-500 insulin with a U-100 syringe, or is it necessary to use a U-500 syringe?

The most common insulin concentration is 100 units per milliliter. The corresponding syringes are u-100, each unit representing 1/100 of a milliliter (0.01 ml).

So, all brands of u-100 syringes are, indeed, measuring the same amount, each unit being 0.01 ml, whether the syringe holds 1.0ml, 0.50ml or 0.30ml. As long as the syringe is marked u-100, the units are the same measure. These syringes MUST be used with insulin that is correspondingly marked as 100 units per ml.

There is also 500 unit (500u per ml) insulin, and in veterinary medicine, there is 40 unit (40u per ml) insulin, just to make sure things are confusing. If you were to use a u-100 syringe with either of these, you would cause a severe overdose/underdose.

It is imperative that the proper corresponding syringe be used. To use the wrong syringe could cause death to the diabetic.

Insulin MUST be drawn up using an insulin syringe (which are typically long and thin to allow you to easily see exactly how much you are drawing up)- the volumes are so small that using even an ordinary 1ml syringe can cause an overdose.

As a safety thing most hospitals I’ve worked have only kept the 100-U insulin in stock.