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Working ScienceArtificial PancreasAn implantable glucose sensor and insulin pump being developed by scientists at the Department of Energy's Lawrence Livermore National Laboratory in partnership with MiniMed, Inc., offers diabetic patients new hope for a more normal life style.
For the millions of Americans with diabetes, life is an endless routine of finger-sticking, glucose monitoring and, for some, insulin injectionsand all are living with the fear of serious health consequences. Doctors say that monitoring blood sugar levels is the best way to help guard against serious complications from diabetes such as kidney and heart disease, blindness, and vascular problems that can lead to stroke and lower limb amputation.
But constant monitoring is not easy or convenient; people don't always want to be vigilant about when and what to eat, or to stop in the middle of everything to prick their fingers several times a day. While new tools for taking blood, measuring glucose, and administering insulin have helped somewhat, they still entail a loss of freedom and require a conscientious effort. An implantable device being developed by scientists at the DOE's Lawrence Livermore National Laboratory in partnership with MiniMed, Inc. of Northridge, California, now offers hope for a more normal life style. Composed of a glucose sensor imbedded under the skin and an insulin pump implanted in the abdomen, the device will work like an artificial pancreas to signal when the body needs insulin and deliver it in precise doses. Insulin pumps are an attractive alternative to injections because they more closely match the natural action of the pancreas by releasing small amounts of shorter-acting insulin. The pumps currently on the market in the United States are about the size of a pager, are worn externally, and deliver insulin through a catheter inserted under the skin. They must be pre-programmed and still require the user to draw blood several times a day.
The new implantable pump, manufactured by MiniMed, is a 2.3-in.-diameter by 0.8-in.-thick titanium disk that includes a reservoir for the insulin. Unlike injections, which can pool insulin in the tissues before it slowly dispenses into the bloodstream, the pump infuses it directly into the abdomen where it is more quickly absorbed. The internal pump is approved for distribution in Europe and is undergoing clinical trials in the U.S. Livermore's new sensor mechanism automates the process by telling the internal pump when to administer the insulin. Adapted from technology used for fusion research at Livermore's Nova laser, the sensor uses fluorescent transducer molecules to measure light reflected in the tissues instead of measuring glucose in the blood. "The detection mechanism uses a molecule that normally has low fluorescence because, once excited by light, electrons are transferred from one part of the molecule to another, preventing bright fluorescence from occurring. When bound to glucose, however, the glucose molecule prevents the electrons from interfering with the fluorescence, and the molecule becomes a bright fluorescent emitter. The more glucose that is present, the more molecules that become bright emitters," explains Stephen Lane, a Livermore physicist and associate program leader of the Medical Technology Program. The fluorescent molecules will be placed within a biocompatible polymer implant being developed by MinMed, and will transmit the information to the pump through a watch-like device worn on the wrist. The sensor components will work in conjunction with the pump, creating a "biomechanical" pancreas. The implant will monitor glucose levels for at least a year before it needs to be replaced. Although the technology is still in the testing stages, Livermore's research team has already received two distinguished awards for their work: an Excellence in Technology Transfer Award from the Federal Laboratory Consortium and an Energy 100 Bright Light Award from the Department of Energy, which honors scientific and technological accomplishments. Media contact: Anne Stark, LLNL, (925) 422-9799, stark8@llnl.gov
. Related information from DOE's Virtual Resource Library:
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