Implantable insulin pumps are emerging insulin-delivery devices that can be surgically implanted under the skin of individuals with diabetes. The pump delivers a continuous basal dose of insulin through a catheter and into the patient’s abdominal cavity. Patients can self-administer a bolus dose with a remote-control device.
These pumps are still used only experimentally in the United States but are available overseas. Initial trials have been encouraging, with patients appearing to experience fewer episodes of hypoglycemia. However, occasional complications have emerged, including blockage of the catheter and infection or other skin conditions at the implantation site.
Eventually, it is hoped that technology will allow implantable insulin pumps to progress to the level of an artificial pancreas. Such a device would not only deliver insulin but also monitor glucose (blood sugar) to determine how much insulin to secrete at a given moment.
About implantable insulin pumps
Implantable insulin pumps are devices that can be surgically implanted in individuals with diabetes as an insulin-delivery device. They are usually placed on the left side of the abdomen.
A continuous basal dose of insulin is delivered through a catheter into a patient’s abdominal (peritoneal) cavity. The patient can also administer a bolus dose of insulin by using a remote-control device. This type of administration allows patients to release insulin depending on the body’s needs, in accord with the treatment plan devised by a physician – for example, to account for meals, exercise and sick days.
The disk-shaped pumps are about the diameter of a hockey puck but much thinner. They weight about 5 to 8 ounces when filled. The reservoir holds up to several months’ worth of insulin and is refilled via a syringe injection through abdominal tissue. Depending on the dosage of insulin, the battery in an implanted pump lasts about eight to 13 years, according to one manufacturer.
An advantage of the implantable pump is that it sends insulin into the peritoneal cavity, where it is quickly absorbed by blood vessels serving the liver, mimicking the body’s natural release of insulin from the pancreas. This delivery system keeps the liver from secreting excess glucose (blood sugar) into the bloodstream.
Implantable insulin pumps were first tried in the 1980s. In the United States, they are still classified as investigational devices and are accessible only in clinical trials. However, they have been available in Europe for several years.
Initial trials of implantable pumps have been encouraging, with patients appearing to experience fewer episodes of hypoglycemia. In a large-scale study conducted by the Department of Veterans Affairs, patients with type 2 diabetes used an implantable pump in an experimental trial. Results indicated these patients had better control of glucose and weight gain than patients who received injections. These patients also said their quality of life was significantly improved while on the implantable pump.
During experimental trials, however, occasional complications related to the pumps have emerged. These difficulties included blockage of the catheter and infection or other skin conditions at the implantation site. There have also been reports of obese patients accidentally injecting insulin refills into their abdomen instead of the pump’s reservoir.
Eventually, it is hoped that implantable insulin pumps will evolve into an implantable artificial pancreas. This device would feature three parts:
- A sensor that monitors blood glucose levels
- An insulin infusion pump
- A computer algorithm that responds to glucose levels by varying the release of insulin
An artificial pancreas would not only deliver insulin but also decide how much should be administered. Researchers are trying to develop an automated internal sensor that can monitor glucose levels. In prototypes of this sensor, body fluids permeate the sensor, which then measures glucose levels. The sensor then transmits information to the pump about the appropriate level of insulin to be delivered.
Most attempts at such a sensor have failed within a few days of implantation, as the sensor becomes covered with fibrous, fatty tissue. This keeps the sensor from performing accurate glucose readings. In addition, problems have been reported with a blockage of the internal catheter that delivers the insulin to the body. However, recent innovations, such as the U.S. Food and Drug Administration’s approval in 2006 of a combined external insulin pump and continuous glucose monitor, hold promise for advances in the implantable pump, artificial pancreas and other diabetes technology.
Questions for your doctor
Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about implantable insulin pumps:
- Are implantable insulin pumps an option for me?
- What are their advantages and disadvantages for me compared to external insulin pumps or other methods of insulin administration?
- Is the implantable pump available in the United States in a clinical trial? If so, what are the criteria, and how do I join?
- Where can I get an implantable insulin pump overseas?
- Will the research project or my insurance cover the surgery, pump and supplies, or is any financial assistance available to me?
- What sort of training will I receive in using my pump?
- What will my basal insulin dosage be? Under what circumstances do I need to add a bolus dose, and how much?
- How long will my pump’s insulin supply last? Will it be easy for me to inject a refill?
- How long is my pump’s battery likely to last?
- How often do I need to perform glucose monitoring?
- Has this device ever malfunctioned? What is my backup plan if there is a malfunction or another glucose emergency occurs?