What is an insulin syringe?
An insulin syringe is a sterile, single-use syringe whose barrel is printed in units for one insulin concentration, either U-100 or U-40.[1] Most are U-100, matching standard insulin with 100 units in each mL.[2] The needle is described by length and gauge, for example 6 mm × 31G.[1]
The three common barrels hold up to 30, 50 and 100 units of U-100 insulin: 0.3 mL, 0.5 mL and 1 mL.[3] The insulin syringe sizes guide compares them line by line.
How an insulin syringe differs from other syringes
The difference is the scale: an insulin syringe counts units, other syringes count millilitres, and insulin pens dial units on a device that should never be drawn into a syringe.
| Device | Scale | Typical capacity | Source |
|---|---|---|---|
| U-100 insulin syringe | Units of U-100 insulin (0.01 mL each) | 0.3, 0.5 or 1 mL | ADA, embecta |
| U-40 insulin syringe | Units of U-40 insulin (0.025 mL each) | 0.3, 0.5 or 1 mL | embecta, BD |
| Tuberculin syringe | mL, lines every 0.01 mL | 1 mL | BD |
| Larger mL syringes | mL | 1 mL and larger | BD |
| Insulin pen | Units, dialled on the pen | Cartridge or prefilled pen | Insulin labels |
BD makes 1 mL syringes with 0.01 mL, U-40 or U-100 graduations, so a barrel of the same size can carry three different scales.[5] Its tuberculin syringe is listed with a 0.01 mL scale.[4] Concentrated insulins at 200 or 300 units per mL come in pens, and their labels say never to transfer them from the pen into a syringe.[6][7] More in tuberculin syringe vs insulin syringe.
U100 syringe: insulin units on the scale
An insulin unit is the dose unit for insulin, and a syringe line equals one unit only when the syringe scale matches the insulin strength. With U-100 insulin in a U-100 syringe, the 10 line is 10 units and 0.1 mL. With any other liquid, the lines are simply 0.01 mL marks; the mg to units calculator and units to mg handle those conversions.
- U-100: 100 units per mL; the standard. See how many units in a mL.
- U-40: 40 units per mL; veterinary insulin. See U-40 vs U-100.
- U-500: 500 units per mL; its own syringe. See U-500 insulin syringe.
Using an insulin syringe safely
Safe use comes down to matching the scale, reading the right line and using each syringe once. The steps the sources describe:
- Match the scale printed on the syringe to the insulin strength on the vial.
- Find the line value: ½, 1 or 2 units depending on the model.[1]
- Draw air equal to the dose, inject it into the vial, then turn the vial upside down.[2]
- Line up the thin black line on the plunger with the dose and remove bubbles.[8]
- Look again to make sure the dose is right.[2]
- Never reuse or share: “One Needle, One Syringe, Only One Time”.[9]
- Put it straight into a sharps container, never loose in the trash.[10]
Practise the readingThe trainer in how to read insulin syringe units draws random 0.3, 0.5 and 1 mL syringes for you to read. Errors to watch for are collected in syringe measuring mistakes, and disposal in how to dispose of syringes.
Syringe sizes beyond insulin syringes
Insulin syringes stop at 1 mL. Anything larger is measured on a syringe marked in mL, which BD makes in 1 mL and larger sizes;[5] the syringe sizes chart lists them up to 50 mL. For a 1 mL insulin syringe in detail, see the 100 unit insulin syringe.
Frequently asked questions
What is an insulin syringe used for?
Measuring and injecting insulin in units. Its scale is printed for one insulin strength, usually U-100.
How many units does an insulin syringe hold?
30, 50 or 100 units of U-100 insulin for the 0.3, 0.5 and 1 mL sizes.
What do the numbers on an insulin syringe mean?
Units of the insulin strength printed on the syringe. On a U-100 syringe, 10 means 10 units, which is 0.1 mL.
What is a U100 syringe?
An insulin syringe scaled for U-100 insulin: 100 units in 1 mL, so each unit line is 0.01 mL. It comes in 0.3, 0.5 and 1 mL sizes.
Can you reuse an insulin syringe?
No. Insulin syringes are sterile single-use devices, and MedlinePlus and the CDC both say never to reuse needles or syringes.
Sources
- Technical data sheet: insulin syringes (Micro-Fine, Ultra-Fine)
- Giving an insulin injection
- 7. Diabetes technology: Standards of Medical Care in Diabetes—2022
- BD SafetyGlide tuberculin syringe, 1 mL (product 305945)
- BD Plastipak 3-piece syringe product family
- Humalog (insulin lispro) prescribing information
- Toujeo (insulin glargine) prescribing information
- Injection technique guide: how to inject insulin with a syringe
- Preventing unsafe injection practices
- Safely using sharps (needles and syringes) at home, at work and on travel