[Discussion] the insulin syringe advice in here is 2 years out of date
the insulin syringe advice in here is 2 years out of date, and I am aware this is a minority view on this board. The numbers the title promised, since a headline without them is worthless: 2 years. Everything below is context for those. Shook the first vial because nobody told me not to. It was fine, but I have…
The arithmetic in full: concentration is mass over volume, so 20mg into 2mL gives 10mg/mL. A U-100 syringe is graduated at 100 units per millilitre, so 5mg is 5 divided by 10 millilitres, which is 50 units.
Spent 18 weeks confused about this until somebody drew the table for me. 20mg, 3mL, 6.67mg/mL, 2mg is 30 units. That is the whole thing.
if the maths gives you a fraction of a unit, change the concentration
Small fix — a U-100 syringe is 100 units per mL. If yours is marked differently it is not U-100 and the whole calculation changes.
twice as much water halves the concentration and doubles the units for the same dose
The arithmetic in full: concentration is mass over volume, so 20mg into 2mL gives 10mg/mL.
Disagreeing with this line only: adding more water is not a safety margin, it is a different divisor.
Yes. Writing 30mg/mL on the vial takes four seconds and removes the entire class of error this board exists to fix.