Many people who take insulin to manage their diabetes inject the insulin with a needle and syringe that delivers insulin just under the skin. Several other devices for taking insulin are available, and new approaches are under development.
Insulin pens provide a convenient, easy-to-use way of injecting insulin and may be less painful than a standard needle and syringe. An insulin pen looks like a pen with a cartridge. Some of these devices use replaceable cartridges of insulin. Other pens are prefilled with insulin and are totally disposable after the insulin is injected. Insulin pen users screw a short, fine, disposable needle on the tip of the pen before an injection. Then users turn a dial to select the desired dose of insulin, inject the needle, and press a plunger on the end to deliver the insulin just under the skin. Insulin pens are less widely used in the United States than in many other countries.
Injection aids are devices that help users give injections with needles and syringes through the use of spring-loaded syringe holders or stabilizing guides. Many of these aids use push-button systems to administer the injection into the infuser instead of through the skin.
External insulin pumps are typically about the size of a deck of cards or cell phone, weigh about 3 ounces, and can be worn on a belt or carried in a pocket. Most pumps use a disposable plastic cartridge as an insulin reservoir. A needle and plunger are temporarily attached to the cartridge to allow the user to fill the cartridge with insulin from a vial. The user then removes the needle and plunger and loads the filled cartridge into the pump.
Disposable infusion sets are used with insulin pumps to deliver insulin to an infusion site on the body, such as the abdomen. Infusion sets include a cannula—a needle or a small, soft tube—that the user inserts into the tissue beneath the skin. Devices are available to help insert the cannula. Narrow, flexible plastic tubing carries insulin from the pump to the infusion site. On the skin's surface, an adhesive patch or dressing holds the infusion set in place until the user replaces it after a few days.
Users set the pumps to give a steady trickle or "basal" amount of insulin continuously throughout the day. Pumps can also give "bolus" doses—one-time larger doses—of insulin at meals and at times when blood glucose is too high based on the programming set by the user. Frequent blood glucose monitoring is essential to determine insulin dosages and to ensure that insulin is delivered.
Injection ports provide an alternative to daily injections. Injection ports look like infusion sets without the long tubing. Like infusion sets, injection ports have a cannula that is inserted into the tissue beneath the skin. On the skin's surface, an adhesive patch or dressing holds the port in place. The user injects insulin through the port with a needle and syringe or an insulin pen. The port remains in place for several days and is then replaced. Use of an injection port allows a person to reduce the number of skin punctures to one every few days to apply a new port.
Approaches Under Development
What are the prospects for an artificial pancreas? To overcome the limitations of current insulin therapy, researchers have long sought to link glucose monitoring and insulin delivery by developing an artificial pancreas. An artificial pancreas is a system that will mimic, as closely as possible, the way a healthy pancreas detects changes in blood glucose levels and responds automatically to secrete appropriate amounts of insulin. Although not a cure, an artificial pancreas has the potential to significantly improve diabetes care and management and to reduce the burden of monitoring and managing blood glucose.
An artificial pancreas based on mechanical devices requires at least three components:
- a continuous glucose monitoring (CGM) system
- an insulin delivery system
- a computer program that adjusts insulin delivery based on changes in glucose levels
CGM systems approved by the U.S. Food and Drug Administration (FDA) include those made by Abbott, DexCom, and Medtronic. A CGM system paired with an insulin pump is available from Medtronic. This integrated system, called the MiniMed Paradigm REAL-Time System, is not an artificial pancreas, but it does represent the first step in joining glucose monitoring and insulin delivery systems using the most advanced technology available.
For more information about CGM systems, see the National Diabetes Information Clearinghouse's fact sheet Continuous Glucose Monitoring or call 1–800–860–8747 to request a copy.
Adapted from NIH Publication No. 09–4643 (May 2009).
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