What Are the Marks on an Insulin Syringe?

Figuring out how to draw correct dosages into an insulin syringe and determining what each line indicates may seem tricky at first, but once you learn the basics, you’ll be able to read the marks on an insulin syringe in no time.

Measurement Units

• Insulin is measured in “units.” The black lines on an insulin syringe indicate how many units the syringe can hold, or, when filled with insulin, how many units of insulin it contains.

Size

• Insulin syringes come in three sizes: 30 units, 50 units, and 100 units.

Identification

• Each black line on a 100 unit syringe indicates two units; each black line on a 50 or 30 unit syringe indicates one unit.

Numbers

• Due to lack of space, only certain lines can be marked with a number. These lines are longer than the others to help them stand out. On a 100 unit syringe, every 10th unit is indicated (i.e. 80, 90, 100), while on the 30 and 50 unit syringes, every fifth unit is indicated (i.e. 75, 80, 85).

Considerations

• The insulin syringes mentioned here are U100 syringes, to be used with U100 insulin, which is the standard in the United States. Syringe sizes and concentrations may differ in other areas.