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Insulin Delivery Devices

by Stacy Griffin, Pharm.D., and Laura Hieronymus, M.S.Ed., A.P.R.N., B.C.-A.D.M., C.D.E.

Insulin is a necessary part of the treatment plan for all people with Type 1 diabetes and many with Type 2. Insulin helps get glucose from the bloodstream into the muscle and fat cells to be used for fuel. It cannot be taken as a pill or a swallowed liquid, because it would be broken down by the digestive system before it reached the bloodstream, where insulin does its work. Instead, insulin is injected or infused into the fatty tissue under the skin.

There are a number of devices that can be used to deliver insulin, including syringes, insulin pens, jet injectors, and insulin pumps. No single device or type of device works well for everyone. The decision of which to use may be based on a person's insulin regimen, ability to manipulate or operate a particular device, visual ability, insurance coverage or ability to afford a particular device and related supplies, occupation, and daily schedule or leisure-time activities. Discussing your needs and preferences with your diabetes care team is the best way to pick the device that will work well for you and get the training you need to use it correctly.

Syringes
The most common method of insulin delivery in the United States is by syringe. Medical syringes are relatively small, are disposable, and have fine needles with special coatings that make injecting as easy and painless as possible. To take insulin with a syringe, the user first pulls back on the plunger to draw in air equal to the amount of insulin to be drawn, inserts the syringe needle into a vial of insulin, pushes the air into the vial, pulls back on the plunger until the correct dose is drawn into the syringe barrel, then inserts the needle through the skin and presses down on the plunger until the barrel is emptied.

People who have difficulty drawing up insulin doses on their own may be able to have a caregiver draw up doses in advance and store the filled syringes in the refrigerator with the needles pointing upward until needed. (Placing the needles in a small cup will keep them upright.) If you use this option, be sure to discuss with your diabetes care team how far in advance syringes can be filled.

Syringes come in a variety of sizes, with different-size barrels, different needle gauges (thicknesses), and different needle lengths. The higher the gauge, the finer (thinner) the needle. Your diabetes care team will help choose the appropriate syringe for you based on the sizes of your insulin doses and your personal preference for needle gauge and length. While some people may prefer a shorter needle, insulin leakage at the injection site or worsening blood glucose control are signs that a longer needle may be necessary to deliver the insulin properly.

Reusing syringes is not recommended due to potential complications such as more painful injections as the needle dulls with use, infection, or tissue damage. The best practice is to use a new syringe for each injection.

If you travel outside of the United States, it is important to be aware that insulin is manufactured in different strengths; however, U-100 (100 units of insulin per milliliter [ml] of fluid) is the most common strength. The syringes for administering insulin are specifically designed for each different strength. Therefore, a U-100 syringe should normally only be used with U-100 insulin. All insulin syringes in the United States are designed for use with U-100 insulin.

While most insulin sold in the United States is U-100, people who are severely insulin resistant may use U-500 (500 units of insulin per ml). However, no U-500 syringes are manufactured, so people who are prescribed U-500 insulin must work with their diabetes care team to learn how to draw up the correct dose in a U-100 syringe.

Injection aids. Various types of injection aids can make injecting with a syringe easier in some situations. Injection aids that hide the syringe needle can be helpful for people with needle phobia. Those that guide or insert the needle into the skin or that insert the needle and inject the insulin can be useful for children who give their own injections, people who have difficulty seeing, or people who have unsteady hands, pain or numbness in their hands, or difficulty manipulating syringes for some other reason. Vial stabilizers and syringe magnifiers may be helpful in drawing up accurate doses of insulin. Brightly colored vial sleeves and caps can help with identifying different types of insulin if more than one type is used.

Before purchasing any kind of injection aid, make sure it is compatible with the type and brand of syringes you use.

Insulin pens
Insulin pens look similar to oversized ink pens, making them a potentially convenient and discreet way of carrying insulin. To use an insulin pen, the pen cap is removed and a pen needle is attached. The pen is then "primed" by dialing in a very small dose (exactly how much depends on the particular pen) and expelling the insulin into the air. Priming is done to ensure that insulin is flowing through the pen properly and that there is no air in the cartridge or needle.

After priming is completed, the actual dose of insulin to be administered is dialed in using a dial or dose knob. The needle is inserted into the skin, and the dose is delivered by pressing on the dose knob until it is fully depressed. It is important to hold the pen in place and to continue pressing the dose knob while counting slowly to five before removing the needle from your skin to ensure that no insulin leaks out. Pen needles are intended for one use only and should be removed and discarded after an injection.

Insulin pens should never be stored with the needle still attached because doing so may allow insulin to leak out or air bubbles to form in the insulin cartridge. Between uses, the pen's cap should be put on to protect the insulin cartridge. In-use pens or pen cartridges should not be stored in the refrigerator because of the possibility that condensation will form in the insulin container. (As soon as an insulin cartridge is placed in a pen, it is considered "in-use" and should no longer be stored in the refrigerator, even if the pen is not actually used for an injection for several days.)

Most pens hold 300 units (3 ml) of insulin and deliver doses in one-unit increments, with up to 60 to 80 units per dose. The NovoPen Junior and the HumaPen Luxura HD deliver insulin in half-unit increments. One of the biggest advantages of insulin pens is accurate dosing. Ease of use is another advantage of pens over syringes because they require less manual dexterity and coordination, and they may be easier to use for people with low vision.

Like syringes, pen needles also come in a variety of needle gauges and lengths. However, pen needles may be slightly thinner and in some cases shorter than syringe needles, so injections may be more comfortable. Some pens are disposable, while others use replaceable cartridges of insulin that are inserted into the pen.

Prefilled pens. Prefilled, plastic, disposable insulin pens have a self-contained insulin cartridge. Several different types of insulin are sold in prefilled pens. Once you have used all of the insulin in the cartridge (or the insulin has reached its in-use expiration date), you dispose of the entire pen.

While most insulin pens look like writing pens, one exception is the InnoLet, a disposable device that looks more like a kitchen timer with a big round dial. The big dial with large, easy-to-read numbers makes the InnoLet easier to use for some people with visual difficulties or dexterity problems. In addition, the relatively large size of the device also may make it easier to hold securely against the skin while administering insulin doses, particularly for people with arthritis, tremors, or shaky hands. The InnoLet holds 300 units of insulin.

Durable pens. Insulin pens that use replaceable cartridges of insulin are also available. Most reusable pens are made of metal but otherwise have about the same features as disposable pens and a comparable cost. One exception is the HumaPen Memoir, which was approved for use in April 2007. It has some additional features, including a memory of the 16 most recent doses delivered (including priming doses) and the time they were administered, as well as a five-second timer to help the user hold the pen in place long enough after injecting.

Jet injectors
Another option that has been available for several years is insulin jet injectors. Jet injectors use a mechanism to produce high-pressure air to deliver a fine spray of insulin through the skin. Once the appropriate dose of insulin has been loaded into the injector, it is placed against the skin and the trigger, or button, is pushed. The high pressure causes the insulin to vaporize and penetrate the skin so that it reaches the subcutaneous tissue. Some bruising may occur from injections using a jet injector, but bruising can be minimized by adjusting the pressure (setting) of the spray. The pressure may have to be adjusted differently for different injection sites.

It is extremely important to follow the manufacturer's guidelines on the care and cleaning of the device to maintain sterility. Jet injectors are generally not recommended for people who take blood thinners, are undergoing dialysis, or have hemophilia.

If you are interested in using a jet injector, work with your diabetes care team to learn the proper technique. In addition, check with your insurer to determine whether the cost of the device is covered.

Inhaled insulin
Inhaled insulin was approved by the Food and Drug Administration in January 2006, but the only inhaled insulin to reach the market so far—Exubera—was discontinued in October 2007. Other drug companies are working to gain approval of their products by the Food and Drug Administration.

External insulin pump
Insulin pumps are becoming more popular as the technology improves and additional features are added. Some pumps are now available that work in conjunction with continuous glucose monitors that can alert the user to high or low blood glucose levels if programmed to do so.

Insulin pumps have traditionally been used primarily by people with Type 1 diabetes, but they are becoming a treatment of choice for many with Type 2 diabetes, as well. Most insulin pumps are small devices about the size of a pager. (The exception is the OmniPod, which is even smaller and is attached directly to the skin, with no tubing necessary.) The pump itself can be clipped onto the waistband of your pants or skirt or placed in a pocket. A length of plastic tubing connects the insulin reservoir within the pump to the infusion set, which is taped onto the skin and contains a small catheter (often called a cannula), through which insulin enters the body. The catheter is commonly inserted into the abdomen or buttocks and needs to be changed every 48 hours.

The pump user programs the insulin pump to deliver insulin at a slow, continuous (basal) rate as well as in supplemental (bolus) doses before meals and to correct for high blood glucose. Basal and bolus dosing most closely resembles how the pancreas releases insulin in a person without diabetes.

Using an insulin pump requires commitment and frequent blood glucose monitoring. According to the American Diabetes Association, people who demonstrate the following characteristics are more likely to do well with pump therapy:

• Strongly motivated to improve glucose control
• Willing to work with their diabetes care team
• Willing to assume substantial responsibility for their day-to-day care
• Able to understand and demonstrate use of the insulin pump
• Willing and able to frequently perform self-monitoring of blood glucose
• Knowledgeable about using their blood glucose monitoring data to make dose adjustments

Many people are willing to put in the work necessary to use an insulin pump because it gives them more flexibility with respect to food choices and the timing of meals and activities, while helping to achieve tighter control of their blood glucose.

Disposal of needles
Most states require that used needles and other "sharps" (such as lancets) be disposed of in a way that reduces the risk of accidental needle sticks. Once you've used a needle or lancet, place it in a puncture-resistant container such as a liquid detergent bottle or a sharps container purchased at your local pharmacy. (When traveling, carry a small container with you.)

Some communities offer a sharps disposal program that allows you to drop off your sharps at particular locations such as hospitals or pharmacies. If your area does not have such a program, discard your puncture-resistant sharps containers by placing the lid securely onto the container, taping it shut, and marking it "USED SHARPS." Place the container in the trash, not in a recycling container. Other options for disposing of sharps include sharps mail-back programs and home needle destruction devices.

Your diabetes care team can help you learn the guidelines that are specific to your state. Another place to find information on relevant state laws and regulations is the Center for Disease Control and Prevention Web site www.cdc.gov/needledisposal.

Traveling with diabetes supplies
When traveling, keep your diabetes supplies with you. Never place insulin or other liquid medicines in checked baggage, where they could be exposed to freezing or very hot temperatures. The Transportation Security Administration currently allows the following items on commercial airplanes once they have been screened at the security checkpoint in the airport:

• Insulin and insulin-loaded dispensing products (vials of insulin, jet injectors, pens, infusers, and preloaded syringes) that are clearly identified with a prescription label containing a name that matches the passenger's name on his ticket
• Other liquid prescription medicines such as Symlin, Byetta, or a glucagon emergency kit that are clearly identified with a prescription label containing a name that matches the passenger's name on his ticket
• An unlimited number of unused syringes, when accompanied by insulin or other injectable medicine
• Clearly labeled nonprescription liquid medicines, such as Regular insulin, which in some states does not require a doctor's prescription to dispense
• Blood glucose meters, test strips, continuous glucose monitors, lancets, and other monitoring supplies
• Insulin pump and insulin pump supplies
• An unlimited number of used syringes when transported in a sharps disposal container or other similar hard-surface container

In general, liquids, gels, and aerosols (such as toothpaste and shampoo) must be in three-ounce or smaller containers and must be placed in a single quart-size, zip-top plastic bag to be brought aboard an airplane. However, there are no limits on the amounts of prescription or over-the-counter medicines that come in a liquid, gel, or aerosol form that may be brought onto an airplane. These items should be packed separately from the items in the quart-size plastic bag.

Cost considerations
Always check with your insurance company to determine whether and which insulin injection devices and supplies are covered by your plan and what out-of-pocket costs are involved. If you do not have insurance coverage (or do not have prescription coverage), many pharmaceutical manufacturers offer patient assistance programs, which offer free or low-cost drugs and supplies to individuals who are unable to pay for their medicine. For more information, look on a specific company's Web site or the Web sites www.rxassist.org or www.needymeds.com, or contact the Partnership for Prescription Assistance either online, at www.pparx.org, or by telephone, at (888) 477-2669.

Making your choice
The basic purpose of all insulin delivery devices is the same: to deliver the desired dose of insulin into the body to keep blood glucose levels under control. The device you choose should be one that's easy for you to use and to afford. But picking one insulin delivery device now doesn't mean you can't switch to another—or to a combination of devices—in the future. If your needs, lifestyle, or fortunes change, you may decide that a different device might work better for you in your new situation.

To learn more about your insulin delivery device options, speak to the members of your diabetes care team, look at the Web sites or call the companies that manufacture such devices, and look for articles and product reviews in reliable Web sites and magazines about diabetes such as this one. You can also check out this comparison chart. Work closely with your diabetes care team to make sure you know how to use the device you choose effectively so that you can take the best care of yourself possible.

Dr. Griffin is a diabetes educator in Lexington, Kentucky, as well as a pharmacist at Central Baptist Hospital in Lexington, Kentucky. Laura Hieronymus has more than 20 years’ experience in diabetes care and education and is a Clinical Management Liaison for Amylin Pharmaceuticals, Inc.

Statements and opinions expressed on this Web site are those of the authors and not necessarily those of the publishers or advertisers. The information provided on this Web site should not be construed as medical instruction. Consult appropriate health-care professionals before taking action based on this information.