Insulin Pens

Written by Kimberly Holland | Published on January 20, 2012
Medically Reviewed by Peggy Pletcher, RD, CDE on April 15, 2014

What Are Insulin Pens?

Managing diabetes often requires taking insulin shots throughout the day. There are many insulin-delivery systems—including insulin pens—that make giving insulin shots much easier. If you currently use an insulin vial and syringe to deliver your insulin, switching to an insulin pen may increase both your compliance to your insulin routine and the ease of taking your insulin shots.

How Do Insulin Pens Work?

Insulin pens come in two basic forms: disposable and reusable. The disposable insulin pens contain a prefilled cartridge and are thrown away when they are empty. Reusable pens require that you replace the insulin cartridge each time it is emptied. These pens do not eliminate your need to poke yourself with a needle; they simply make measuring and delivering your insulin easier. Insulin pens hold between 21 and 80 units of insulin at a time and can deliver insulin in increments of one-half unit, or one unit, or two units. The maximum dose that can be delivered at one time varies between pens.

Unlike vials of insulin, insulin pens do not require constant refrigeration. Insulin pens only require refrigeration until their first use. After the initial use, simply keep your insulin pen out of direct sunlight in a room temperature setting. Insulin pens typically stay good for use for 28 to 31 days after the initial use, depending on the type of insulin they contain, unless the expiration date printed on the pen or cartridge has passed.

The insulin pen you use depends on the type of insulin you require, the number of units you typically need per insulin shot, and the available pens for that insulin. Work with your doctor or healthcare provider to figure out which pen is right for you.

Each time you use your pen:

  • Check the expiration date and type of insulin if you have more than one type of pen.
  • Check to make sure that your insulin is not clumpy and that your fast-acting insulin is clear and colorless.
  • Roll the pen in your hands, and then gently tilt the pen if it is an insulin mix.
  • Remove the pen cap and clean the top with sterile alcohol.
  • Attach the needle to the pen.
  • Prime the pen, and then dial up the correct dose. Double-check the dose before you inject.
  • Remove the cap and inject the insulin using good injection techniques (inject into a clean site, and hold the needle at a 90 degree angle unless you are thin).
  • Push the button to inject the insulin and wait five to ten seconds to be sure all of the insulin has been absorbed.
  • Remove the needle and dispose of it properly. Use a new needle each time.
  • Replace the disposable needle, mix your insulin, ensure that your insulin looks right inside the pen, and dial in the insulin dosage you need to inject.Typically, you hear a clicking noise for each increase in insulin unit, making insulin pens user-friendly for people with vision problems. The number of units dialed in also appears inside a window on the pen so you can double-check your dose.

If you accidentally dial in too high of a dose, insulin pens give you the ability to fix your mistake quickly and easily. Some pens expel the excess insulin through the needle in such a way that it will not enter your skin, while others have an option to reset your pen to zero units and start over.

Inject the insulin in a similar manner to the way you inject your insulin using a syringe: Press the button on your pen to disperse the insulin into the fatty layer under your skin. Hold the pen in place, with the button held in for five to ten seconds to ensure that all the insulin enters your skin.

Are There Any Risks?

If you fail to check your insulin or the expiration date of your insulin, the insulin may not work correctly. Expired insulin does not work as well as insulin that is not expired. If the insulin has any kind of particles in it, do not use it. These particles may plug the needle and prevent you from delivering a full dose of insulin.

Dialing in too high of a dose and not double-checking the dosage may result in the delivery of too much insulin or too little insulin. If this occurs, monitor your glucose levels closely after the injection. Too much insulin may cause your blood sugar levels to drop too low; too little insulin may cause your blood sugar to increase to dangerously high levels.

The needles on insulin pens come in different lengths and thicknesses, and most fit on all of the available insulin pens. Talk to your doctor or healthcare provider to decide which needle is best for you..

What the Expert Says

“It is very important that patients and physicians have confidence in the accuracy of their chosen insulin pen,” says a study published in the May 2008 issue of the Journal of Diabetes Science and Technology. “This is a prerequisite for good metabolic control, regardless of the pen type used.” The study found that some pens deliver less insulin than they are designed to administer. To help build your confidence in your pen and ensure your pen’s accuracy, regularly monitor your blood sugar level before each meal and at bedtime. If you feel that your pen regularly fails to deliver the proper amount of insulin, contact your doctor.

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Show Sources

  • Gebel, E. (January 2010). Insulin Pens. Diabetes Forecast Magazine. Retrieved on November 26, 2011, from
  • Information About Insulin. (June 2004). New York University Medical Center. Retrieved on November 26, 2011, from
  • Pen Devices for Insulin Administration. - Prescription Drug Information, Interactions & Side Effects. Retrieved from November 26, 2011, from
  • Hänel, H., Weise, A.,, Sun, W., Pfützner, J.W., Thomé, N., & Pfützner, A.. (May 2008). Differences in the Dose Accuracy of Insulin Pens. Journal of Diabetes Science and Technology, 2(3): 478-481.

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