Insulin Delivery Systems - On The Horizon: Diabetes

Content provided by the Faculty of the Harvard Medical School

Insulin delivery systems

Several new devices may revolutionize how insulin is delivered, or at least offer you more ways to get the insulin you need.

Implantable insulin pump

Large clinical trials have tested pumps that are surgically implanted under your skin, usually into the wall of your abdomen, and programmed to deliver insulin into your abdominal cavity or a large vein. Like the external insulin pump, they can closely imitate the action of a normal pancreas and eliminate the need for multiple insulin doses every day. About the size of a hockey puck, these pumps are regulated by a hand-held remote-control device and programmed to release insulin continuously. They can also be set to release an extra dose of insulin at mealtime. Depending on your insulin requirements, the pump's reservoir has to be filled, using a small needle, every one to three months. Its battery lasts about four years.

Studies found that people who use this pump maintain near-normal blood sugar levels without having more hypoglycemic reactions, which is often a problem with intensive therapy using external pumps or multiple injections. The biggest disadvantage is that the pump's catheter, which feeds insulin to the cavity of the abdomen or through a vein, occasionally gets clogged and must be cleared. Sometimes this requires a minor surgical procedure.

The cost is also a limiting factor because it's expected to sell for $10,000–$15,000, not including the cost of surgery to implant the device. Finally, the pumps currently available can't adjust insulin delivery automatically because no practical means of continuous glucose monitoring has been developed. In order to "instruct" these pumps, you'll still have to rely on frequently checking your glucose levels. Implantable pumps remain in the research phase and are not yet approved for sale in the United States.

Photo courtesy of Medtronic MiniMed, Inc. Implantable pumps, which are surgically placed under the skin, deliver doses of insulin throughout the day.

Oral insulin

Insulin cannot be taken orally because digestive juices destroy it before it can be absorbed. However, in animal studies, a polymer-coated oral insulin has successfully lowered blood sugar levels. The polymer gel protects the insulin from stomach enzymes by shrinking. It then expands and releases the insulin in the intestine, where the environment is more hospitable to absorption. The capsule must undergo more study before it can be tested in humans.

Insulin patch

Researchers are also working on a skin patch that could supply a continuous low dose of insulin. To adjust the dose before meals, users could simply pull off a tab on the patch to release insulin. Studies on animals have shown promise, but in humans so far the patches can provide only low insulin doses.

Last updated:	January 23, 2007