While there are a number of different brands and models available, most insulin pens fall into one of two groups: reusable pens and disposable pens.
Before using a reusable pen, you must load it with a cartridge of insulin (sold separately usually in boxes of five cartridges). Cartridges used in the U.S. today hold 150 or 300 units of insulin. Depending on the size of your doses, a cartridge may give you enough insulin to last for several days of injections. When the cartridge is empty, you throw it away and load a new cartridge. With good care, a reusable pen can often be used for several years.
Disposable pens come filled with insulin and are thrown away when they're empty. Most disposable pens used in the U.S. today hold 300 units of insulin and are sold in boxes of five.
Disposable pens are generally more convenient than reusable pens because you don't need to load any cartridges, but they usually cost more to use than reusable pens and cartridges.
Pen brands and models differ from one another in many ways. When choosing a pen, there are many factors to keep in mind, including:
- The brands and types of insulin that are available for the pen.
- The number of units of insulin that the pen holds when full.
- The largest size dose that can be injected with the pen.
- How finely the dose can be adjusted by the pen. For example, one pen may dose in two-unit increments (2, 4, 6, etc.), another in one-unit increments (1, 2, 3, etc.) and yet another in half-unit increments (1/2, 1, 11/2).
- The way the pen indicates whether or not there's enough insulin left in it for your entire dose.
- The size of the numbers on the pen's dose dial and whether they're magnified.
- The amount of strength and dexterity required to operate the pen.
- How to correct a mistake if you dial the wrong dose into the pen.
- The way the pen indicates whether or not there's enough insulin left in it for your entire dose.
Advantages and Disadvantages
The reasons why some insulin users prefer insulin pens include:
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Insulin pens are portable, discreet, and convenient for injections away from home.
They save time because there's no need to draw up insulin from a bottle - it's already pre-filled in the self-contained cartridge.
They usually let you set an accurate dose by the simple turn of a dosage dial, and that may make it easier to set an accurate dose for people who have vision or dexterity problems.
There are also reasons why insulin pens aren't right for all users, including:
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Insulin in pens and cartridges is often more expensive than insulin in bottles for use in syringes.
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Some insulin is wasted when pens are used: one to two units of insulin are lost when the pen is primed before each injection; and there's usually some insulin left in the pen or cartridge (but not enough to inject) when they're used up.
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Not all insulin types are available for use in insulin pen cartridges.
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Insulin pens don't let you mix insulin types, which means that if the insulin mixture you need isn't available as a pre-mix, two injections must be given - one for each type of insulin.
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Insulin pens should only be used for self-injection. This is because the pen needle must be removed from the pen after each injection, and there isn't a way to completely protect the person giving the injection from getting accidentally stuck by the needle while he/she is removing it from the pen.
Hope this tells you what you wanted to know about pens.
Warren