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July 29, 2010

Wireless sensor watches blood sugar for diabetics

Commentary by Greg Szto: At last, a report on a wireless system that will measure blood glucose continuously and transmit the information wirelessly. Now, if this information is then fed back into an insulin pump, then we have a closed loop biological system….

By Maggie Fox, Health and Science Editor (Science Translational Medicine journal)

WASHINGTON | Wed Jul 28, 2010 4:04pm EDT

(Reuters) – Researchers have developed an implantable sensor that measures blood sugar continuously and transmits the information without wires — a milestone, they said, in diabetes treatment.

The device worked in one pig for more than a year and in another for nearly 10 months with no trouble, they reported in the journal Science Translational Medicine.

It takes the diabetes field a step closer to development of an “artificial pancreas” — a device that can replace natural functions to control how the body handles blood sugar.

And it would be handy for people who need to check blood sugar daily, such as patients with type 2 diabetes, the team at the University of California San Diego and nearby privately held GlySens Inc wrote.

“You can run the device for a year or more with it constantly working, and recording glucose quite satisfactorily,” bioengineering professor David Gough, who led the study, said in a statement.

“We hope to begin the first human trial in a few months,” Gough added in a telephone interview.

He said his team has been testing such experimental devices in pigs for 31 years.

Medical device makers have been working to develop a so-called artificial pancreas to deliver insulin to patients with type 1 diabetes, an autoimmune disease in which the body destroys its own ability to make insulin and thus to properly break down sugar.

Even with treatment, eventually blood vessels and organs get damaged and patients can lose vision, organs and limbs. An estimated 3 million Americans have type 1 diabetes, usually diagnosed in childhood or in young adults.


Gough’s team said their device could also work for people with type 2 diabetes, which is far more common and becoming worse. An estimated 180 million people globally have diabetes.

The implant used in the pig study is about 1.5 inches in diameter, and 5/8 inch thick. “We hope to make it smaller in the future,” Gough said.

It transmits 10 to 12 feet.

The device uses a sensor that detects oxygen in the tissue where it is implanted to measure glucose. “The present artificial pancreases use needle-like sensors or wire-like sensors,” Gough said. “This device is likely to be more appealing to people with diabetes. There is nothing protruding from the body.”

To inject insulin or use an insulin pump, patients need input on blood glucose levels. Too little insulin and patients get damage from hyperglycemia, or too much blood sugar.

Too much insulin and hypoglycemia — dangerously low blood sugar — can send patients into a coma.

Gough foresees ways to have the glucose monitor send its signals to cell phones.

“There are parents with diabetic children who spend their nights worrying that their child in a nearby bedroom may go into nocturnal hypoglycemia,” he said. An implanted sensor could wake a parent if the child’s glucose levels dropped to a dangerous level.

The Juvenile Diabetes Research Foundation, which helped pay for the study, has been working with several companies to create a seamless artificial pancreas. It works with U.S. drugmaker Johnson & Johnson’s unit Animas, which makes insulin pumps, and DexCom Inc, which makes continuous glucose monitoring devices.

Smiths Medical, a unit of Smiths Group Plc, Abbott Diabetes Care, a unit of Abbott Laboratories Inc, and Medtronic Inc also make glucose and insulin devices.

Gough and colleagues at the university founded GlySens and the company collaborates with the institution.

The article abstract:

Sci Transl Med 28 July 2010:
Vol. 2, Issue 42, p. 42ra53
DOI: 10.1126/scitranslmed.3001148

  1. David A. Gough1,*,
  2. Lucas S. Kumosa1,
  3. Timothy L. Routh2,
  4. Joe T. Lin2 and
  5. Joseph Y. Lucisano2

+Author Affiliations

  1. 1Department of Bioengineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0412, USA.

  2. 2GlySens Incorporated, 6450 Lusk Boulevard, Suite E-109, San Diego, CA 92121, USA.
  1. *To whom correspondence should be addressed. E-mail: dgough@ucsd.edu

An implantable sensor capable of long-term monitoring of tissue glucose concentrations by wireless telemetry has been developed for eventual application in people with diabetes. The sensor telemetry system functioned continuously while implanted in subcutaneous tissues of two pigs for a total of 222 and 520 days, respectively, with each animal in both nondiabetic and diabetic states. The sensor detects glucose via an enzyme electrode that is based on differential electrochemical oxygen detection, which reduces the sensitivity of the sensor to encapsulation by the body, variations in local microvascular perfusion, limited availability of tissue oxygen, and inactivation of the enzymes. After an initial 2-week stabilization period, the implanted sensors maintained stability of calibration for extended periods. The lag between blood and tissue glucose concentrations was 11.8 ± 5.7 and 6.5 ± 13.3 minutes (mean ± standard deviation), respectively, for rising and falling blood glucose challenges. The lag resulted mainly from glucose mass transfer in the tissues, rather than the intrinsic response of the sensor, and showed no systematic change over implant test periods. These results represent a milestone in the translation of the sensor system to human applications.

Citation: D. A. Gough, L. S. Kumosa, T. L. Routh, J. T. Lin, J. Y. Lucisano, Function of an implanted tissue glucose sensor for more than 1 year in animals. Sci. Transl. Med. 2, 42ra53 (2010).