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Units are a ruler, not a dose

People argue about units like the mark on the syringe is the medicine. It isn't. A unit on a U-100 insulin syringe is a line on a ruler. Units are one of five different numbers that show up in the same conversation. A milligram, a milliliter, a unit, a gauge, and a length are not the same thing.

100 units = 1 mL. 10 units = 0.1 mL. 1 unit = 0.01 mL.

That is the whole definition. It is true on a 0.3 mL syringe, a 0.5 mL syringe, and a 1 mL syringe, as long as the syringe says U-100. The barrel size changes how long the ruler looks. It does not change the math. Ten units is still a tenth of a milliliter.

What the ruler does not know is how many milligrams are floating in that tenth. That number is the concentration. Concentration is milligrams divided by milliliters.

Say the container holds 10 mg and someone added 1 mL. Concentration is 10 mg per mL. Then 0.1 mL, which is 10 units, holds 1 mg.

Say the next container also holds 10 mg, but someone added 2 mL. Concentration is 5 mg per mL. The same 10 units now hold 0.5 mg. Same mark on the ruler. Half the material. The video that said "I do 10 units" did not tell you which of those two worlds they live in.

This is the harm. Not the existence of a syringe. The harm is borrowing a mark from a stranger whose liquid is a different strength, then trusting the mark as if it were a milligram.

If a prescriber or a pharmacist already gave you a milligram number, you can turn it into a volume:

• volume in mL = milligrams you were told, divided by mg per mL
• U-100 units = that volume times 100

If they did not give you a milligram number, the calculator will not invent one. Neither will this page. Run your own numbers.

A finished pen is a different object. Lilly pens are not a vial plus a ruler. If that is the product in your hand, read Lilly, not a comment section: lilly.com.

Research vials sold here are not a prescription and they are not for people or animals. The ruler math is still the ruler math. It applies to any dry material once liquid is in the bottle. It is not permission, and it is not a protocol.

연구용 바이알. 21세 이상. 사람이나 동물에게 쓰지 않습니다. 의학적 조언이 아닙니다.