Insulin Pens

Insulin pens come with preloaded insulin for giving insulin injections. There are several types on the market, including “smart” or connected insulin pens. Your healthcare provider will go over the ins and outs of using them.


Insulin Pen

What is an insulin pen?

An insulin pen is an injection device that you can use to deliver preloaded insulin into your subcutaneous tissue — the innermost layer of skin in your body. These pens are one form of insulin therapy for people with diabetes. They’re a type of multiple daily injection (MDI).

An insulin pen looks like a writing pen. But it has a single-use needle for its point and insulin as its “ink.” There are several types of insulin pens.

Parts of an insulin pen

While there are several types of insulin pens, they all have similar basic parts, including:

  • Insulin reservoir: This is a clear plastic container that holds the insulin in the pen. You can see the “quality” of the insulin (like if it’s cloudy or clear) and how much insulin is left in the pen. Some pens have insulin cartridges (reservoirs) that you can replace. Other pens are disposable — you throw them away once the insulin reservoir runs out.
  • Pen cap: The cap protects the insulin reservoir from damage when you’re not using the pen.
  • Rubber seal: The rubber seal is where you connect a single-use needle for an injection.
  • Needle: Needles for insulin pens are single-use, which means you only use them for one injection and then throw them away. Each needle comes in a sterile protective container. You remove the needle from the container and attach it to the pen before an injection. Pen needles come in different sizes. Talk to your healthcare provider to choose the pen needle that’s best for you.
  • Dosage knob: This is a knob you turn to select the insulin dose you need.
  • Dosage window: This shows the number of units of insulin you select using the knob.
  • Injection button: Once you inject the pen needle, you press the injection button to give the insulin dose.
  • Label: The label tells you the type and brand of insulin in the pen and its expiration date.

Types of insulin pens

There are several types of insulin pens on the market. They vary based on:

  • If they’re disposable or reusable: Some pens are disposable — you throw out the whole pen after the insulin reservoir runs out or the insulin expires. Other pens are reusable — you replace the insulin reservoir with a new one (a cartridge) and use the same pen again.
  • The type of insulin they use: Manufactured insulins work differently based on how long it takes for them to start working and how long they last in your body. Specific insulin pens may only be for certain types of insulin, like long-acting, rapid-acting, intermediate-acting or short-acting insulins. Some pens use mixed insulin types.
  • If they have digital components or not: Some insulin pens have a digital app, which can help you remember things like when you last injected insulin and how much you received. These may be called “smart,” or “connected,” insulin pens. Other pens are “manual,” meaning there’s no digital app. You may have to write down how much you injected in a logbook to keep track of it.
Smart, or connected, insulin pens

Smart insulin pens are digital, connected (through the internet) pens that automatically send information about the time and amount of insulin you received in an injection to an app on your mobile device (typically a smartphone). A smart pen may be an entire insulin pen or it may be a cap you attach to certain existing pens. The app may have additional functions, like:

  • Keeping track of active insulin in your system.
  • Helping calculate the bolus (insulin amount) based on your current blood sugar level and/or the number of carbohydrates you’re going to consume. Some smart insulin pen systems also connect with a continuous glucose monitor (CGM) to do this.
  • Sending you alerts if it thinks you may have missed an insulin injection around your typical mealtimes.
  • Monitoring the insulin’s temperature and expiration date.

Talk to your healthcare provider if you’re interested in learning more about smart insulin pens.


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How do you use insulin pens?

Before an injection, select a clean, dry work area. The supplies you’ll need include:

  • The prescribed insulin pen. If you use more than one insulin pen, make sure you select the correct one for your needs.
  • A pen needle and alcohol wipe.
  • A container for used needles. You can use a hard plastic container with a screw-on or tight lid, or a commercial “sharps” container.

Step-by-step instructions for preparing your insulin pen include:

  1. Wash your hands.
  2. Remove the cap of the insulin pen.
  3. If the insulin in the pen appears cloudy, roll the pen in your hands and turn it from side to side for one full minute. You don’t have to roll the pen if the insulin is completely clear. Do not shake the pen.
  4. Wipe the rubber stopper with an alcohol wipe.
  5. Attach a new pen needle to the insulin pen. To attach the pen needle, pull the paper tab off the pen needle, screw the new needle onto the pen, and remove the outer cap of the needle. You’ll need the outer cap to remove the needle from the pen when you’re done with the injection. Remove the inner cap.
  6. Prime the insulin pen. Priming means removing air bubbles from the needle. It ensures that the needle is open and working. You must prime the pen before each injection. To prime the insulin pen, turn the dosage knob to the 2 units indicator. With the pen pointing upward, push the knob all the way. At least one drop of insulin should appear. You may need to repeat this step until a drop appears.
  7. Select the dose of insulin that has been prescribed for you by turning the dosage knob.
  8. Check that the dose is correct. Set the pen down without letting the needle touch anything.

Step-by-step instructions for injecting with an insulin pen include:

  1. Using the hand you write with, wrap your fingers around the insulin pen, keeping your thumb free to push down on the injection button.
  2. Insert the needle with a quick motion into your skin at a 90-degree angle. The needle should go all the way into your skin.
  3. Slowly push the injection button of the pen all the way in to deliver your full dose. Remember to hold the pen at the site for 6 to 10 seconds, and then pull the needle out.
  4. Carefully place the outer cap on the needle, unscrew the needle (the needle should come off with the outer cap), and drop it into your container for used “sharps” equipment.
  5. Put the pen cap back on and store it at room temperature.

You may bleed at the spot of the injection. If you notice bleeding, apply pressure with a clean alcohol wipe or cotton ball. Cover the injection site with a bandage if necessary.

How long do you hold an insulin pen?

After you inject the insulin into your skin, you should hold the insulin pen there for 6 to 10 seconds to make sure the insulin absorbs. You can then remove the needle from your skin.

Where do you inject with insulin pens?

Recommended insulin pen injection sites include your:

  • Lower belly.
  • Front and side of your thighs.
  • Upper and outer arms.
  • Buttocks.

Do not inject:

  • Within 2 inches (5 centimeters) of your belly button (navel).
  • The middle of your abdomen.
  • Into or near scar tissue or stretch marks.
  • Near joints.
  • Your groin area.

You’ll also need to rotate, or change, your injection sites. If you use the same site repeatedly, you may develop hardened areas under your skin (lipohypertrophy). It can also cause lipodystrophy, which is a complete or partial loss or abnormal distribution of fat tissue (adipose tissue) in the affected area. These conditions keep the insulin from working properly. Rotating your injection sites will make your injections easier, safer and more comfortable.

If you’re going to use the same area, inject at least 1.5 inches away from the last spot where you injected. Depending on which type of insulin you’re taking, different parts of your body may absorb the insulin differently.

How do you dispose of insulin pens?

Each time you use a needle, you should dispose of it in a needle-safe “sharps” container. If you have a disposable insulin pen, you can throw it away (without a needle attached) in your regular trash once the insulin is gone or expired.

Risks / Benefits

What are the pros and cons of insulin pens?

Compared to using a syringe and vial of insulin, people typically find insulin pens easier to use. If it’s difficult for you to hold an insulin vial and draw up insulin, pens may be a better option. In addition, studies show that insulin pens have improved dosing accuracy and consistency compared with syringes.

Some people prefer insulin pens over insulin pumps due to the freedom of not having a device attached to them.

The potential negative sides of using insulin pens include:

  • Based on your healthcare insurance, insulin pens may be more expensive than using syringes with a vial of insulin.
  • Insulin pens still require multiple daily injections (more needle injections), compared to insulin pump therapy. This may result in more frequent skin bruising.


What are the side effects of insulin pens?

The most common side effect of any insulin injection, including insulin pens, is low blood sugar (hypoglycemia). Low blood sugar happens when the level of sugar in your blood falls below 70 milligrams per deciliter (mg/dL).

Be sure you know how to treat low blood sugar before you start using insulin.

When To Call the Doctor

When should I see my healthcare provider?

If you’re starting to use insulin pens for the first time, you’ll meet with a healthcare provider who’ll teach you how to use the pen. This will likely be a certified diabetes care and education specialist (CDCES). Don’t hesitate to ask questions.

While using insulin pens, you’ll see your diabetes provider regularly to make sure your treatment plan is working well for you. If you often have high blood sugar and/or low blood sugar, reach out to your provider. You likely need to adjust your insulin requirements.


Additional Common Questions

Do insulin pens need to be refrigerated?

You can store open insulin pens at room temperature — about 68 to 72 degrees Fahrenheit (20 to 22 degrees Celsius). Be sure to avoid temperatures that are too hot or too cold. This can change how the insulin works.

You should store unopened pens in a refrigerator. They’ll be good until the expiration date that’s printed on the box. Write the date on the insulin pen when you first open it. Most pens are good for 28 days once you open them.

Check with your pharmacist or read the insulin pen’s drug insert for exact instructions on temperature limits and expiration dates.

What’s the difference between an insulin pen and a cartridge?

Some insulin pens are reusable and have cartridges of insulin that you can replace within the pen once one runs out. Other insulin pens are disposable — you throw the whole pen out once it runs out of insulin or expires.

Care at Cleveland Clinic

A note from Cleveland Clinic

Insulin pens are one option if you need to take insulin to manage diabetes. There are a lot of different pens out there, so you may feel overwhelmed at first. The good news is that your healthcare provider will be by your side to help you figure out which insulin pen is best for you. They’ll also go over how to use the pen and answer any other questions you have.

Medically Reviewed

Last reviewed on 02/12/2024.

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