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.