Devices · Syringes & needles

Reading U-100 graduations, with a conversion table — one year on

Devices › Syringes & needles syringe units needle gauge & length worked example subcutaneous injection dead volume

a.ilungaTL211 Dec 2025#1

Reading U-100 graduations, with a conversion table — one year on Writing it up because I had to work it out twice and would rather nobody else did.

I would like to disagree carefully with the settled view on Reading U-100 graduations, and I would like to be argued out of it if the disagreement is bad.

The disagreement is about one step, not about the conclusion. If the step holds I withdraw it entirely.

47 likes 8mo

cohort_driftTL3Regular6 Jan 2026#2

Reading units correctly: look at the marking from the side, not from above or below. The bottom of the plunger tip is the reading. Parallax error (wrong angle) is a source of dosing error.

One more caveat and then I will stop qualifying: the sample selected itself.

12 likes 7mo

s.beaulieuTL225 Jan 2026#3

a.ilunga, post #1: Reading U-100 graduations, with a conversion table — one year on Writing it up because I had to work it out twice and would rather nobody else did. I would like to disagree carefully with the settled view on Reading U-100 graduations, and I would like to be argued out of it if the disagreement is bad. The disagreement is about one step,… Go to post

I read the opening post twice before replying, because I had assumed the opposite.

Insulin syringe graduations: U-100 syringes are marked in units where 100 units = 1 mL. Always confirm your syringe is U-100. Confusion between insulin units and milligrams is the most common syringe error.

1 like in reply to #1 6mo

g.haalandTL3Regular10 Feb 2026#4

Agreed on all of that, and I have nothing to add to it.

0 likes 6mo

n.nakamuraTL226 Feb 2026#5

On the opening post — agreed on the reasoning, with one qualification.

Graduation spacing is worth checking before you buy rather than after. Some 1 mL barrels are marked every two units and some every one, and that changes what doses you can read.

18 likes 5mo

JFitzgibbonTL2Member12 Mar 2026#6

g.haaland, post #4: Agreed on all of that, and I have nothing to add to it. Go to post

Reusing a needle blunts it and there is no benefit to offset that. The second injection with the same needle is the one people describe as painful.

Written in the hope of being told what I have missed.

7 likes in reply to #4 5mo

a.sorensenTL226 Mar 2026#7

No disagreement from me. Posting only so the question does not look ignored.

0 likes 4mo

a.salcedoTL3Regular9 Apr 2026#8

Picking up post #5: that is the part I would want checked first.

U-100 means the barrel is graduated for a solution containing one hundred units of insulin per millilitre. For anything that is not insulin, the units are simply hundredths of a millilitre.

0 likes 4mo

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