By: Cindy Onufer
Insulin delivery devices come in many shapes and sizes. The most familiar and widely used in the United States is the traditional insulin syringe.
Many people with diabetes who require insulin therapy are choosing multiple daily insulin injections (MDI) in an effort not only to achieve tighter control of glucose and prevent complications but also to have flexibility in meal planning and exercise.
MDI consists of providing optimal doses of both basal (background) insulin and bolus (mealtime) insulin. The new rapid-acting insulin for bolus needs must be injected within 15 minutes of a meal. Because the dose of rapid-acting insulin can be matched to the amount of carbohydrate in the meal, this gives great freedom in choosing the type of food and portion size. That is the good news—flexibility. On the other hand, how many people want to carry vials of insulin and syringes to restaurants, picnics or work sites?
A Better Option?
Another option—perhaps the best one, short of insulin pump therapy—is to consider the use of insulin pens. They are highly accurate in dosing, offer convenience and portability, and are easily used discreetly in public.
The insulin pen is by far the preferred method of insulin delivery in Europe and most other industrialized countries. In the United States, insulin pens were introduced by Novo Nordisk in 1987, but their adoption was very slow even though they were given away free by the manufacturer through physicians’ offices and diabetes educators.
An article by DaCosta, Brackenridge and Hicks in the January/February 2002 issue of Diabetes Educator states that insulin pen use in the United Kingdom is approximately triple that in the United States. The authors describe the routine nature of showing an array of available insulin pen devices to patients with type 1 and type 2 diabetes needing insulin therapy. They emphasize this as part of tailoring an insulin regimen to meet a patient’s needs.
Patient preference and satisfaction with insulin pen use were shown in a U.S. clinical trial conducted by Nancy Bohannon, MD, and myself (Diabetes, May 2000, abstract 1483-PO), in which 60 subjects used Becton-Dickinson (BD) 1.5 mL pens for all insulin use. Twenty-two subjects had previously used some other pen injection device, and 38 had never previously used an insulin pen. At the conclusion of the study, all subjects completed a survey about their experience with the insulin pen. Ninety-eight percent said they preferred to continue using pens for insulin delivery.
So why are insulin pens so underutilized in the United States? It may be that neither physicians nor people with diabetes are aware of the availability and varieties of insulin pens. Certified Diabetes Educators (CDEs) are often the first to show insulin pens to people with diabetes. (See the chart on pages 48-50 for descriptions of the pens available today.)
Three Types of Pens
Currently available insulin pens come in three types:
- Reusable cartridge pens designed to allow the user to load insulin cartridges. The user dials in the desired insulin doses until the cartridge is emptied and then must insert a new cartridge. These pens hold either 1.5 mL cartridges (150 units) or 3.0 mL cartridges (300 units).
- Disposable prefilled pens containing either 1.5 mL or 3.0 mL of insulin in a reservoir that is not replaceable.
- Reusable open system pens. This unique system from Disetronic allows the use of any type of U100 insulin. The user fills disposable 3.15 mL cartridges. The Disetronic pen delivers insulin in single-unit increments from 1 to 80 units per injection and shows the dosage on an electronic display.
To use an insulin pen for subcutaneous injections, a pen needle must be attached. Pen needles are double-ended so that one end pierces the rubber diaphragm of the insulin cartridge or reservoir. Pen needles are available from BD, Novo Nordisk and Owen Mumford in several gauges and lengths.
Not Necessarily “Either-Or”
Some people choose to use an insulin pen for mealtime bolus insulin delivery, but continue to use syringes for bedtime basal insulin. The newest approach to basal insulin—Lantus (insulin glargine)—is available only in a vial in the United States. Aventis—which makes Lantus—plans to have a prefilled Lantus insulin pen available in the future. This is already an option in Europe.
The B-D Pen Mini that holds a 1.5 mL insulin cartridge delivers insulin in 1/2-unit increments. This is ideal for insulin-sensitive people who want to deliver insulin in doses between 1/2 and 15 units in one injection. It’s not only children with diabetes who can benefit from this. My adult patients also like the colorful design on the Mini pen that distinguishes it from the standard BD pen (which delivers in 1-unit increments). This distinction keeps them from grabbing the wrong pen as they leave home for the day.
What’s New—and the Power of Two
Novo Nordisk has launched the first “smart pen” in the U.S. market. The Innovo is a 3.0 mL insulin pen that remembers the last dosage of insulin and also how many hours have elapsed since the last injection was taken.
Taking it one step further, the Novo Nordisk InDuo is an integrated system that contains an Innovo insulin pen plus a OneTouch Ultra blood-glucose meter by LifeScan. Ideally, the Innovo pen could be used to deliver a basal insulin, while the on-the-go InDuo system could be used for the mealtime rapid-acting insulin NovoLog (aspart), with the dosage determined by the pre-meal blood-glucose results of the Ultra meter and the meal’s carbohydrate count. Novo Nordisk has even color-coded the Innovo pen differently from the color trim of the InDuo system to help promote their utilization as a basal/bolus system.
These pens with memory might be the jump-start needed to regain interest in insulin pens in the United States. Back in October 1997, Diabetes Health devoted a full page to my personal perspective in an article titled “Czechs Out Diabetes Care in Central Europe.” During a trip to Prague, I was privileged to spend a day at a renowned diabetes care center. Not only did I see that insulin pens accounted for 80 to 90 percent of all insulin delivery in the Czech Republic, but also they gave me a popular “smart pen,” called the Optipen, to bring back and show my colleagues.
Well, we’re catching up to the Europeans finally. If you are a person with diabetes wanting to see the insulin pen options available to you, call your CDE for a demonstration.
Match Your Insulin Delivery Needs to the Design of the Pen
Consider the maximum size dose possible per injection with each pen and also the increments of dosage. Do you need 1/2 or 1-unit increments?
The Novo Nordisk Prefilled pens (in 70/30, NPH or Regular) can deliver dosages only in 2-unit increments (such as 2, 4 or 6 units) but cannot, for example, deliver a 5-unit dose.
Consider your preference for pre-filled disposable pens versus reusable pens in which you replace cartridges of insulin as needed.
Try handling the pen you are interested in. Does it feel comfortable when you dial in the dose? Can you easily see the dosage amount?
Check with your health insurance. While pen delivery is only slightly more expensive than vial and syringe use, you may need to convince your insurance plan to cover this option. Pre-filled disposable pens cost more than the ongoing use of a reusable pen.
Recently, I heard of several patients denied coverage for 3.0 mL prefilled pens that are available only in sets of five. Some of these patients were able to get approval for insurance coverage for 3.0 mL insulin cartridges and pen needles to use in a pen obtained for free in a manufacturer promotion.
Tips for the Proper Use of Insulin Pens
Never carry an insulin pen with the needle attached. Put the pen needle on right before an injection and remove it following the injection.
According to Becton-Dickinson product research, when you go from a warm to a cold place, the insulin shrinks and air enters the cartridge through the needle. When extra air dilutes the insulin in the cartridge, your dose won’t be correct. When you go from a cold to a warm place, the insulin swells and leaks out through the needle. If you use cloudy insulin such as NPH or 70/30, fluid may leak out while particles stay in, which will change the strength of the insulin.
A patient shared this story with me: When traveling abroad on an airplane, he forgot to remove the pen needle, and the change in cabin pressure caused all of the insulin in the cartridge to leak out. Luckily, he had another cartridge with him in his carry-on bag. He did remember the advice to always keep your insulin with you. Checked baggage is exposed to very cold temperatures that will destroy insulin. Plus, checked baggage may get lost!