Insulin Syringes

If you have any questions about which insulin syringes to use, please post on Talking TR for assistance.



U100 U40 syringe comparison The top photo is a U40 syringe which come with red caps and needles covers, and are also available with red unit marks. U40 syringes are made to hold 20.0u of U40 insulin or less, and are difficult to find with half unit marks.  U40 insulin must be used with U40 syringes. 

We recommend using the syringe in the bottom of the photo which is a 3/10cc (ml) 100 syringe, for use with 30.0 units or less of U100 insulin.  They have orange caps and needle covers.  U100 syringes come with both full and half unit marks.  Syringes with half unit marks make measuring the small increments given on TR much easier and more accurate. If from Europe, the description is 3/10ml, for 30 units or less, demi (descriptor for half unit markings).  The cc and ml unit of measurement is the same.  U100 syringes can be utilized with U40 insulin by using the conversion chart.

Half Unit Marks Half unit marks make for much easier measuring of half and quarter units, as well as the "fats and skinnies" we use when dosing our cats on TR.  Most vets do not support the use of U100 syringes with U40 insulin.  Using the conversion chart for U40 insulin and U100 syringes, we are able to much more accurately measure very small increments of insulin.  

Most U40 insulin syringes do not have half unit marks, so accurate and consistent measuring of small doses is far more difficult.

Syringe with Half Unit Dosing Increments


For more information, click here.     

Syringe gauge examples The gauge of U100 syringes varies from 25 gauge (thickest) to 33 gauge (thinnest).   The most commonly found 3/10cc syringes with half unit marks are found in gauges 29, 30 or 31.    While a thinner gauge needle may hurt less during injection, the thinner the gauge, the more chance the needle may bend when giving shots.  
Needle Lengths The needles on insulin syringes come in two lengths, 1/2" (longs - left photo) or 5/16" (shorts - right photo).  Some people find short needles are sometimes easier to control. Longer needles tend to work better for cats with a thicker layer of fat, getting in past the fat layer for better insulin  absorption.  The choice to use longs or shorts is generally a matter of personal preference. 
Syringe Bevel Many find there are better absorption results if the bevel of the syringe is facing outwards when giving shots.  Injecting with the bevel side facing up/out allows for the needle to slide into the skin much easier resulting in shots being less painful. For more information click here.
Used Needles Insulin syringes are meant to be used one time only.  In an emergency, they can be cleaned with vigorous rubbing alcohol rinses, but this is not recommended unless absolutely necessary.  When the needle is inserted, chunks of skin clog the needle; the tip of the needle become blunt hurting more when injected into the skin.  To learn more about needles damaged by reuse, click here. 
Sharps container More than a billion insulin syringes, needles, and lancets are used for diabetes care in the United States alone each year. If they are not disposed of properly, these items, known as "sharps", can injure other people.

The rules and regulations regarding sharps disposal may be different in towns and counties around the world.  Please check with your local sanitation or health department for information about how to dispose of used syringes properly. 


Graphics courtesy of  Becton, Dickinson and Company