Quick Answer: To read an insulin syringe correctly, identify the unit markings on the barrel, match your syringe type (U-100 or U-40) to your insulin, and measure the dose from the top ring of the plunger. Always double-check for accuracy to ensure safe and effective diabetes management.
Insulin syringes have unique unit measurements that are specific to insulin dosages. Therefore, learning how to read and use insulin syringes accurately is absolutely crucial for good diabetes management. So, here’s our comprehensive guide!
Related article: Does Insulin need to be refrigerated? how to Store it Correctly?
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For a more dynamic experience, watch the video below.
Different Types of Insulin Syringes
Insulin syringes, sometimes called "diabetic syringes," come in different sizes and types to meet individual needs. They may differ in size, needle length, gauge, and unit measurement:
Related article: Can you Prefill Insulin Syringes & How Long Are They Good for?
U-100 and U-40 syringes
Insulin syringes come in two main types: U-100 and U-40. The difference lies in the concentration of insulin, and choosing the correct syringe is crucial for safe and accurate dosing. Using the wrong syringe can result in incorrect insulin levels, leading to hyperglycemia (high blood sugar) or hypoglycemia (low blood sugar).
Here’s a breakdown of these two syringe types:
✅ U-100 Syringes
- Designed for U-100 insulin, which contains 100 units of insulin per milliliter.
- The most commonly used type in the U.S. today.
- Marked with units to ensure precise dosing.
✅ U-40 Syringes
- Made for U-40 insulin, which contains 40 units of insulin per milliliter.
- Less common but still used for certain types of insulin, especially for pets.
- Requires careful measurement to avoid dosing errors.
👉 Always double-check that your syringe matches the concentration of your insulin before injection to prevent serious health risks.
Syringe sizes
The size of an insulin syringe refers to its maximum capacity in milliliters. Typically, U-100 insulin syringe sizes range from 0.3 ml to 1 ml. 0.3 ml syringes can draw 0.3 ml of insulin, 0.5 ml syringes can draw 0.5 ml, etcetera.
Because a U-100 insulin contains 100 units of insulin per milliliter of fluid:
- A 0.3 ml syringe can hold up to 30 units of insulin.
- A 0.5 ml syringe can hold up to 50 units of insulin.
- A 1 ml syringe can hold up to 100 units of insulin.
Therefore, 0.3 ml syringes are designed to be used for insulin doses under 30 units, while 0.5 ml syringes are for 30 to 50 units and 1 ml syringes for higher doses up to 100 units.
Related article: How to Calculate Your Insulin Dose Correctly?
Needle gauge and length
Insulin syringes may come in different needle sizes too. The gauge is the thickness of the needle. Insulin syringes typically have a gauge between 27 and 31, with a higher gauge indicating a thinner needle. Needle lengths usually range from 4 mm to 12.7 mm.
Ask for your doctor’s advice on what needle gauge and length are best for you. Besides comfort during the injection, several individual factors must be considered, including the type of insulin you're using and the thickness of your subcutaneous tissue.
Related article: The Ultimate Guide to Insulin Pen Needle Sizes!
The different parts of an insulin syringe
Before learning how to read an insulin syringe, it's helpful to be familiar with its different parts:
- The needle.
- The barrel is the part that holds the insulin. It is marked with measurements to indicate the amount of insulin being drawn into or expelled from the syringe.
- The plunger is the movable part used to draw insulin into the barrel and inject it.
- The cap is the removable protective cover that protects the needle to prevent contamination and accidental needle sticks.
Some insulin syringes may also have additional features, such as a safety shield, a protective mechanism, or a detachable needle that can be replaced after each use.
How to Read Insulin Syringes (U-100)
Insulin syringes look similar to regular syringes but are numbered in units. As you know, insulin is measured in units, not mL, unlike most other injectable medications.
Therefore, the numbers on an insulin syringe indicate the number of insulin units being drawn.
For U-100 insulin syringes, each line on the syringe barrel represents one unit of insulin. Depending on the syringe size, it may have markings up to 100 units. For example, a 1 ml U-100 insulin syringe will have markings up to 100 units, while a 0.5 ml U-100 insulin syringe will have markings up to 50.
When drawing insulin into a syringe, always read from the top ring (the needle side). Once you have identified the increments on the syringe barrel, you can measure the amount of insulin by counting the number of lines from the needle end to the desired amount of insulin. For example, if you need to measure 20 units with a U-100 insulin syringe, you will draw the plunger to the line marked "20" on the syringe barrel.
Related article: How to Convert Insulin Units to mL?
How to inject insulin with a syringe?
Unlike prefilled insulin injector pens, using insulin syringes requires drawing the insulin dose from a vial into the syringe to prepare your subcutaneous injection.
This gesture may seem daunting at first, but it will quickly become second nature with practice. It’s quite simple, but it must be done correctly to ensure you receive your full insulin dose. Here are the steps to follow:
- 🧼 Wash your hands.
- 🧴 Gather your injection supplies (insulin vial, syringe, alcohol swabs, and sharps container).
- 🩹 Prepare the injection site.
- 💉 Prepare the syringe: Remove the needle cap and pull back the plunger to draw air into the syringe equal to the amount of insulin you need to inject.
- 🔄 Inject the air into the vial.
- 📏 Draw your dose of insulin.
- 💉 Inject the insulin: Hold the syringe like a pencil and insert the needle into the skin at a 90-degree angle. Push the plunger down slowly to inject the insulin. Wait for 10 seconds.
- 🗑 Remove the needle.
- ♻️ Dispose of the syringe in a sharps container.
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📌 Key Takeaways:
✅ Understand Insulin Syringes: Insulin syringes come in U-100 and U-40 types, and using the correct one is essential for accurate dosing.
📏 Choose the Right Syringe Size: Syringes range from 0.3 ml to 1 ml, holding up to 30, 50, or 100 units of insulin, depending on the dose needed.
💉 Check Needle Gauge & Length: Insulin syringes vary in needle thickness (gauge 27-31) and length (4 mm to 12.7 mm) for comfort and effectiveness.
🔢 Read Insulin Syringes Correctly: Insulin is measured in units, not mL, and the plunger should be aligned with the correct marking on the syringe barrel.
🗑 Follow Proper Injection Steps: Always sanitize, measure accurately, inject correctly, and dispose of used syringes safely to avoid errors and contamination.
💬 We'd Love to Hear From You!
What about you? Do you use insulin syringes or insulin pens? Have you ever struggled with reading syringe measurements or getting the right dose? Share your experiences, tips, or questions in the comments—your insights could help others in their diabetes journey!
📆 Article Update History:
✅ Updated: March 12, 2025
Originally Published: April 24, 2023
Comments
4AllFamily Customer Care Team said:
Dear Car,
You are absolutely right, this was a typo! I’ve immediately corrected it.
Thanks a lot for seeing it and taking the time to let us know!
Best regards.
4AllFamily Customer Care Team
Car said:
in your step 5 you say to “inject the air into the syringe” this is super incorrect. You need to inject the air into the vial in order to overcome the negative pressure within the vial so you can actually draw up the insulin. Super important to be careful about steps like this. Cheers!