Insulin therapy is the only treatment for people with type 1 diabetes and insulin-dependent type 2 diabetes. Unfortunately, insulin isn't available in tablets or pills; the only way to administer it is through subcutaneous injections.
There are several insulin delivery devices on the market, and new ones are being developed as we write. There are three ways to take insulin today: injectable pens, syringes, and insulin pumps. Insulin injectable pens are the most prescribed ones.
But using an insulin pen for the first time is daunting, and while your doctor or diabetes nurse has shown you the process, you may still be hesitating to do it by yourself. It's perfectly normal.
So, here’s a thorough guide on insulin pens. What are they? How to use them correctly? How to avoid painful insulin injections? Are they better than syringes or pumps?
Related article: Does insulin need to be refrigerated, and how to store it properly?
What’s an Insulin Pen?
An insulin pen is an insulin delivery device preloaded with insulin to facilitate subcutaneous injections. Novo Nordisk launched the first insulin pen in 1985,a significant improvement in insulin therapy, blood sugar management, and the patient's quality of life.
While there are different types of insulin pens, all share the same basic parts, including:
- An insulin reservoir made of clear see-through plastic.
- A dosage knob to dial the number of insulin units you want to inject.
- A window that shows the number of insulin units selected.
- An injection button to press down for the injection.
- A rubber seal to connect the needle
- to the pen.
- A pen cap that protects the insulin from light and ambient conditions when not in use.
- Disposable needles for each insulin injection (not included).
Insulin pens may be filled with bolus, basal, or premixed insulin.
Related article: A beginner’s guide to basal and bolus insulins.
Reusable vs. disposable insulin pens
There are two main types of insulin pens: reusable and disposable. A disposable insulin pen comes with a prefilled insulin cartridge and is fully discarded after use. On the contrary, reusable insulin pens work with replaceable insulin cartridges that are loaded into the pen.
Smart insulin pens
Smart insulin pens are relatively new insulin delivery devices. They're like basic insulin pens but come with added innovative technology. For example, smart pens use Bluetooth technology to send dose information to a smartphone app. Most diabetes device manufacturers now offer smart insulin pens, including Medtronic and Novo Nordisk.
Smart pens are helpful for calculating and tracking insulin doses, sending reminders, and ultimately optimizing blood sugar control. They can also help deliver more accurate half-unit insulin doses, prevent missed shots, keep track of insulin expiration dates and storage conditions, etc.
Related article: What happens if you miss a dose of insulin?
FlexPen, KwikPen, and Solostar
Currently, there are 4 main disposable insulin pen brands in the U.S.: FlexPen, FlexTouch, KwikPen, and Solostar. While they're all very similar, they differ in specificities like size, ergonomics, injection force, and unit precision.
FlexPen and FlexTouch insulin pens are used by Novo Nordisk and are available for the following insulins: Fiasp, Levemir, Novolog, Tresiba U-100, and Tresiba U-200.
KwikPen is manufactured by Eli Lilly Diabetes and used for Humalog, Basaglar, and Humulin insulins.
Solostar insulin pen is from Sanofi and delivers Lantus, Admelog, Apidra, and Toujeo insulins.
Reusable insulin pens include NovoPen (Novolog insulin), AutoPen (Humalog insulin), HumaPen(Humalog insulin), and others.
Check how many of your insulin pens can fit into our portable insulin coolers!
How much insulin is in a pen?
Most disposable insulin pens and cartridges for reusable pens contain 3 mL of insulin.
Now, how many doses of insulin are in a pen also depends on the insulin concentration. For example, most insulins are U-100 (100 units of insulin per mL of solution), meaning most insulin pens contain 300 units of insulin. However, if you use U-300 insulin (300 units per mL), a 3 mL pen has 900 units.
Related article: How to convert units to mL?
How to choose insulin pen needles?
Whether disposable or reusable, insulin pens work with disposable needles. You must use one needle per injection, which makes about 365 needles per year if you’re doing one insulin injection a day, 730 for 2 daily injections, and 1460 for 4 daily injections!
Most insulin pen needles fit on most insulin injection pens. But there are two things to consider when choosing insulin pen needles:
- The needle length. Disposable needles for insulin pens range from 4 mm to 12 mm in length.
- The needle diameter or "thickness." Disposable insulin pen needles range from 29 to 32 gauge in diameter.
Both the gauge and length contribute to perceptions of pain when injecting insulin with a pen. The shorter and thinner the needle is, the less pain. But some diabetic patients might need long, thick needles. Price is also a factor to consider when buying insulin needles.
Eventually, your doctor and pharmacist will advise you on what needles are best for you.
Related article: How to help and support your diabetic partner?
How to Use an Insulin Pen?
While insulin therapy seems daunting at first, using an insulin pen is easy once your know the steps. And because you have to use it so many times (at least once and sometimes up to 8 times a day), you'll become an insulin pen expert in no time!
Getting into good habits from the beginning is essential, and learning how to use an insulin pen correctly helps prevent painful shots, skin issues, possible infections, and, most importantly, dosage mistakes.
Here’s a step-by-step guide to taking insulin with an injectable pen:
Step 1: Check your blood sugar
Check your blood sugar with your blood glucose monitor before every insulin injection, especially rapid-acting one before a meal. It allows to:
- Adjust the dose of bolus insulin depending on your pre-meal blood glucose.
- Ensure your blood sugar level isn't too low before injecting any insulin.
- Keep track of your blood sugar and insulin doses on a log, so your healthcare provider can help you analyze, adjust, and optimize insulin therapy.
Step 2: Prepare supplies & wash your hands
The first time you use an insulin pen may be daunting for some patients. An excellent way to get through it calmly is to prepare all your supplies beforehand. Put the following diabetes supplies on a dry and clean area:
- Insulin pen
- Pen needles
- Alcohol wipes (2)
- Sharps container
Then, wash and dry your hand before taking the following steps and proceeding to the injection.
Step 3: Load, check, and prepare your pen
If you use a reusable pen, insert the insulin cartridge into the pen first. You do not have to do that with a disposable pen, as the insulin is already inside.
Before using your insulin pen, always check the expiration date. Remember that insulin has two expiration dates: the one labeled on the pen and the one occurring about one month after the first time it's been used or taken out of the fridge.
Then, remove the pen cap and visually inspect the insulin inside. Most insulins are clear water-like liquids. If clear insulin looks cloudy or has lumps inside, it's a sign it may have gone bad, so do not use it.
However, NPH or premixed insulins are normally cloudy. You must mix these insulin suspensions before using your injectable pen. Gently roll the pen between your palms, then move it up and down (without shaking it to avoid bubbles). Cloudy insulin is ready when it looks milky white.
Related article: Clear vs. cloudy insulins: Why it matters!
Note: If your insulin pen was refrigerated, let it sit for a few minutes until the insulin comes to room temperature. While you can inject cold insulin, it’s generally more painful.
Step 4: Connect the needle to the insulin pen
Once you've ensured the insulin inside your pen is safe and ready for use, you must connect the needle to the pen. Always use a new needle for each injection. Start by wiping the rubber seal with an alcohol wipe.
Insulin pen needles come with a protective paper tab, an outer needle cap, an inner needle cap, and the needle inside. Here’s how to attach your needle to your pen:
- First, pull the paper tab off the needle.
- Screw the needle onto the rubber seal of the pen.
- Remove the outer cap (keep it on the side for later use).
- Remove the inner cap (you can throw this one away)
Step 5: Prime your insulin pen
You must prime your insulin pen before each injection. Priming helps remove air bubbles and make sure the needle isn’t blocked. Here’s how to prime:
- Select 2 units of insulin with the dosage knob.
- Hold your pen with the needle pointing upward.
- Tap the pen gently to move air bubbles to the top.
- Next, push the injection button all the way in to inject insulin into the air.
- You must see at least a few drops of insulin going out of the needle. If not, repeat and prime again until a drop appears and there are no more bubbles inside your pen.
Step 6: Select your dose of insulin
Next, select the dose of insulin that has been prescribed for you. Look at the dose window and make sure your pen is set at zero. Then, turn the dosage knob until the arrow points to the number of insulin units you want to inject. Always double-check that the dose is correct before injecting.
Note: when an insulin pen is empty or almost empty, the dosage knob does not turn anymore. In that case, throw the pen or cartridge away and get a new one to inject your full insulin dose. Do not try to split the dose into 2 injections.
Related article: What to do if you run out of insulin?
Step 7: Choose & clean your injection site
Insulin pens can be injected subcutaneously into the stomach, arms, thighs, and buttocks. The preferred injection site is the abdomen because the insulin is absorbed more quickly. It's a little slower when injected in the upper arm and even more in the thighs and buttocks.
You must rotate the injection site and change the spot each time you inject insulin with a pen or a syringe. Using the same location every time can cause skin problems and impair insulin absorption.
Before injecting insulin with a pen, gently clean the skin at the chosen injection site with an alcohol swab.
Step 8: Inject the insulin with the pen
Now that everything is ready, here’s how to inject your insulin dose with an insulin pen:
- Hold the insulin pen with the hand you write with, keeping your thumb free to push the injection button.
- With the other hand, gently pinch up your skin.
- Then, in a quick motion, insert the whole needle into your skin at a 90-degree angle.
- Push the injection button all the way in and hold the pen for an additional 10 seconds until the dose is fully administered.
- Check that the number in the dose window is back to zero.
- Pull the needle straight out of your skin.
Note: You may sometimes bleed at the injection site. Apply light pressure with your finger.
Step 9: After the insulin pen injection
Once you’ve removed your insulin pen from the skin, put the outer needle cap back on the needle, unscrew the needle, and dispose of it in a sharps container.
Put the insulin pen cap back on. It protects your insulin from light and ambient conditions. Keep your insulin correctly stored until the next injection.
How to Store an Insulin Pen?
Insulin is a fragile and temperature-sensitive medicine that requires specific storage conditions. For safe use and optimized effectiveness, store your insulin pen as follow:
- Before opening, keep your disposable insulin pens or replaceable insulin cartridges refrigerated between 36°F and 46°F / 2°C and 8°C until the expiration date labeled on the pen.
- Once open or left out of the fridge for more than a few hours, keep your insulin pens at room temperature (below 77°F / 25°C) for about a month.
Different insulins may have a different shelf life. Always check the storage instructions on your box of insulin pens. For more detailed information about insulin pen storage, check the following article:
Related article: Why does insulin need to be refrigerated?
Protecting insulin from heat and light puts an extra challenge for those traveling with diabetes. 4AllFamily designs the most convenient and highest-performance travel coolers for refrigerated medications like insulin.
Please browse through our catalog of insulin cooling and transportation solutions, and do not hesitate to reach out for help and advice.
Related article: How to keep insulin cold on a plane?
Pros and Cons of Insulin Pens
Insulin devices and technologies are changing rapidly, and while most insulin-dependent diabetics still use traditional insulin pens or vials and syringes, there’s an expanding array of new possibilities. So, let's compare insulin pens to their older alternative (vials and syringes) and their newer ones (insulin pumps).
Insulin pen vs. syringe
Insulin pens are more convenient to use than insulin vials and syringes. They’re small, portable, simple, and discreet to use.
Syringes are a bit more complicated to use. Unlike insulin pens, you must draw insulin from a vial into the syringe. In addition, there are more risks of breakage as the small glass vials are very fragile and shatter easily when dropped on a hard floor.
Insulin pens are a more convenient and accurate insulin delivery solution than syringes. But, on the other hand, they're more expensive.
Insulin pens vs. pumps
Insulin pens and insulin pumps are both convenient and efficient ways to administer insulin therapy to diabetic patients. Surprisingly, while insulin pumps are new high-technology medical devices, they may not always be the best solutions. Several factors must be considered when choosing pens vs. pumps.
Related article: Can you shower or swim with an insulin pump?
Pros of insulin pumps over pens:
- No more injections.
- Insulin pumps offer more flexibility with insulin delivery than pens.
- More precise insulin dosing.
- Fewer risks of missing a dose of insulin.
- Most people find pumps more convenient than pens.
- A better blood sugar control.
Pros of insulin pens over pumps:
- No device attached to your body 24/7
- Pens are simpler to use. They do not require complex programming and manipulation.
- No risk of technical issues and failure of insulin delivery.
- You have fewer supplies to carry with pens. Insulin pumps require backup and infusion set supplies.
- Fewer skin issues with pens than with pumps.
- Pens are more affordable than pumps.
Ultimately, the most important thing is that you are comfortable with your insulin therapy device and find the right balance between your diabetes treatment and your lifestyle.
Related article: A parent’s guide to a safe and happy childhood with diabetes
Trusted Sources & References:
 Kesavadev J, Saboo B, Krishna MB, Krishnan G. Evolution of Insulin Delivery Devices: From Syringes, Pens, and Pumps to DIY Artificial Pancreas. Diabetes Ther. 2020 Jun;11(6):1251-1269. doi: 10.1007/s13300-020-00831-z. Epub 2020 May 14. PMID: 32410184; PMCID: PMC7261311. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7261311/