Understanding Insulin Syringes Sizes

Understanding Insulin Syringes Sizes

The Basics of Syringes and Needle Sizes

There are more than 34 million people in the United States living with diabetes. Somewhere in the neighborhood of 7.5 million of these individuals require insulin treatments to manage their blood sugar, and the majority of these individuals choose insulin syringes as their delivery mechanism.

While new advancements in administering insulin have been introduced that provide more convenient and easier options to those with diabetes, including insulin pens and insulin pumps, the insulin syringe remains a common choice often due to cost and insurance coverage.

In this post, we’ll cover the different sizes of insulin syringes and needles, pointing out the uses and advantages of each. However, before continuing we are obliged to remind you that all decisions regarding your diabetes treatment, including insulin injections, should be made with your diabetes physician and care team. Never make any adjustments to your diabetes treatment plan without first consulting your physician.

The Three Sizes of Insulin Syringes

Insulin syringes come in three common “barrel” sizes. They are:

The size of the barrel determines how much insulin the syringe can hold. Therefore, determining what syringe size works best for you really depends on your insulin dosage each time you administer it. As a rule, the syringe sizes work like this:

  • 0.3 mL syringes are for insulin doses under 30 units. These syringes are usually measured in one-unit intervals; however, some are available that are measured in half units.
  • 0.5 mL syringes are for insulin doses between 30 and 50 units and are also usually measured in one-unit intervals.
  • 1.0 mL syringes are used for doses above 50 units of insulin and can draw up to 100 units. These syringes are usually measured in two-unit intervals.

Which Syringe Size Is Right for Me?

Again, this depends on your insulin dosage and treatment schedule. However, it’s usually recommended that you use the smallest syringe size that accommodates your dosage requirements. For example, if you administer 20 units of insulin, then a 0.3 mL syringe is probably the best choice. If you administer 55 units, then a 1.0 mL syringe is necessary.

Here’s another consideration. If your insulin dosage lies on the high end of a syringe’s capacity, it might be wise to choose the next size up. For example, 49 units of insulin can fit into a 0.5 mL syringe, however, it leaves you little wiggle room if for any reason your doctor decides to up your dosage to 51 units. So, you might be better off going with a 1.0 mL syringe just in case any adjustments are necessary.

Additionally, most people taking insulin to manage their blood sugar require a minimum of two injections each day. Some people can need up to seven injections per day. The dosages for each injection may vary, so you might need to keep more than one size syringe handy.

What About Very Small Insulin Doses?

People who are prescribed very small insulin dosages (6 units or less), many of whom are children, should try to find a 0.3 mL syringe measured in half units as this makes it easier to draw in a more precise dosage.

Understanding Syringe Needle Sizes

Syringe needles are sized using two different measurements - length and gauge. As you can imagine, needle length determines how far a needle can penetrate the skin. Needle gauge determines the “thickness” of the needle, which can play a big role in the comfort and ease of injections.

Needle Length

Needle lengths commonly range from 4 millimeters to 12.7 millimeters (1/2”). The trend in recent years has been to go with shorter needles because this poses less intramuscular risk. As you probably know, insulin should be administered just under the skin and not injected into the muscle that lies beneath. Shorter needles are safer, simply because they avoid going too deep.

Longer needles have been recommended in the past for individuals with higher Body Mass Indexes (BMI). It was believed that the added length was necessary to penetrate thicker layers of subcutaneous tissue in individuals with severe weight concerns.  However, recent studies point to the fact that shorter needles can be just as effective at delivering insulin in obese individuals, and, in fact, pose less risk of intramuscular injections, as well as site bruising, pain and other detrimental side effects.

Needle Gauge

Measuring needle gauge (or thickness) can seem a bit counterintuitive because the higher the number, the thinner the needle. They generally range between 28G and 31G, with the 31G being the thinnest needle. So, what’s the difference?

First and foremost, the thinner the needle, the less pain you’re likely to feel at the injection site. That’s why most people these days are opting for higher gauge needles. There is one big consideration, however. Thinner needles cannot pass large amounts of medicine quickly. So, if you require large insulin doses, you’ll be pushing down on that stopper a lot longer if you use a thinner needle. It very well might be worthwhile to choose a lower gauge (wider needle). Granted, it might sting a bit more than a thinner needle, but you will deliver your insulin faster and more efficiently, which can help you avoid insulin leakage problems and other issues.


There are a number of factors to consider when choosing an insulin syringe and needle size. What will work best for you depends on your individual insulin requirements, frequency of daily doses, body type, and personal comfort concerns. That’s why the right syringe choice can only be determined by sitting down and discussing the situation with your diabetes physician and care team.

Purchasing Insulin Syringes

One aspect of using insulin syringes, regardless of barrel and needle size, is that you will go through multiple syringes each day (never reuse syringes or needles as this poses serious health concerns). Depending on your insurance coverage, you might be responsible for some or all of the cost of your syringes. One way to save money and add a whole lot of convenience to the process is to shop online. Licensed online suppliers such as Diabeticteststrips.org provide a wide range of syringe options from top manufacturers, including Clever Choice, Easy Comfort and BD Ultra-Fine, as well as other diabetic supplies at prices that can be up to 65% less than those found at your local pharmacy. You’ll save yourself a trip to the store and likely a good deal of money, too.


Diabeticteststrips.org is a trusted supplier of diabetes care products and accessories. For more information and to explore a complete range of products, including glucose meters and test strips, insulin syringes, pen needles, continuous glucose monitoring systems, and more, visit www.Diabeticteststrips.org.

Back to blog

Leave a comment

Please note, comments need to be approved before they are published.