The U.S. Food and Drug Administration approved last year a prefilled disposable long-acting insulin pen with the highest capacity yet, made by Sanofi. The device holds 900 units. What does that mean? Insulin is administered in unit increments. The recently approved insulin pen can provide up to 160 units per millimeter in a single injection, and may reduce the number of injections for adults with diabetes. Most insulin pens deliver up to 60 or 80 units per injection, adjustable in one-unit increments. They typically have capacities of 300 to 600 units. Depending on the patient, therefore, the number of injections or doses in insulin pens can vary. Many patients wind up requiring 30 units per injection.
There are many colors and styles of insulin pens, but they all more or less follow the same design guidelines. At a glance, an insulin pen could easily be mistaken for a large permanent marker because it has a shirt-pocket clip and a cap that protects the needle. (Needles are sold separately.) Major insulin pen makers develop and market pens with different types of insulin, so they typically use color and shape to indicate the type and brand of insulin the pen contains. If you do not like the way an insulin pen looks, it is possible to find a different color or style manufactured by another company that produces a comparable product. But options are limited.
The amount of insulin a patient needs depends on his or her specific condition. Doses are adjustable in insulin pens by using their “dial-a-dose” feature, typically measured in one-unit increments. Insulin pens contain 3 milliliters of insulin but the concentration of insulin varies. When someone suffering from Type 2 diabetes begins using insulin, it is common to start with a small dose and increase it incrementally until an ideal dose is achieved. Many people with Type 2 diabetes will start with 1 to 2 units of insulin for every kilogram (2.2 pounds) of body weight. A person weighing 176 pounds, for example, might start with one 12-unit injection per day.
4. Needle length
One of the biggest issues for diabetics is that they have to self-administer injections, typically on a daily basis and often more than once per day. Insulin pens are designed to make this as painless and easy as possible, replacing the old-fashioned needle-and-syringe routine, which is not only cumbersome but also a challenge for patients who lack hand-eye coordination, such as the elderly. Needles, which are sold separately from insulin pens, come in different lengths, from 4 millimeters to 12.7 millimeters. The shorter needles work best for most adults and children, but consult with your doctor about what length works best for your specific needs because needle length can affect blood sugar control.
5. Needle gauge
Another factor to consider with insulin pen needles (which are sold separately) is the gauge, or thickness. A thinner needle tends to mitigate the discomfort of injection. However, a thicker needle delivers the insulin dose more quickly. Needles should not be used more than once due to risk of infection. Doctors typically prescribe the needle along with the insulin, but it does not hurt to ask if you are being prescribed the shortest and thinnest needle possible for your specific needs. Also remember that when discussing needle gauge, the smaller the number the thicker the needle. Insulin pen needle gauges range from 29 to 33.