Device Provides Accurate, Noninvasive Way to Measure Blood Glucose in Diabetics

From the WebMD Archives

Nov. 11, 1999 (Los Angeles) -- Diabetics may soon have a new device that makes frequent, automatic, painless, and accurate glucose measurements possible to help them maintain close control of their condition. This tight glucose monitoring could help prevent the serious complications of this disease. The device, called the GlucoWatch® automatic glucose biographer, is expected to be available by the summer of 2000.

GlucoWatch works through a process called iontophoresis, in which the application of a mild electric current to the skin promotes the transport of glucose through the skin, where the device can sense and measure it. The device can be strapped to the forearm like a watch and takes about 20 minutes to come up with an accurate glucose reading. It is designed to measure glucose three times an hour for up to 12 hours.

In a study published in the Nov. 17 issue of the Journal of the American Medical Association, investigators at two diabetes centers and three contract research organizations around the country studied 155 GlucoWatches in 92 adults who had diabetes. Sixty-three subjects wore two devices. Up to three measurements were obtained each hour and compared to glucose measurements taken from blood samples obtained twice an hour from the fingertip. Diet and insulin, the medicine diabetics use to control their glucose levels, were manipulated to produce a broad range of blood glucose levels.

According to the authors, led by Janet A. Tamada, PhD, of Cygnus Inc., in Redwood City, Calif., one of the greatest potential advantages of this device is its ability to determine trends and patterns in glucose concentration. This will allow the patient to keep his or her glucose levels within tight limits and avoid the large swings that can occur when the condition is not under optimal control. They conclude that the accuracy of this device compares well with that of devices that are currently available. Cygnus Inc. is the company that developed the GlucoWatch.

"The [GlucoWatch] biographer is designed to work in 12-hour cycles, so patients would only have to wear it at night" or during any other period in which they wanted to keep careful watch over their glucose levels," says Russell Potts, PhD, vice president of research at Cygnus.


Other than mild skin irritation where the device is worn, there are no adverse effects. However, wearing the device during exercise or very hot weather could be "a problem because there's a lot of glucose in sweat," which could distort the reading. Therefore, he tells WebMD, the device has been "designed to measure sweat." At a certain sweat level, the biographer will stop measuring glucose until sweating subsides. "We'd rather tell people it's not measuring, rather than give them a reading that's way wrong."

Cygnus expects to have the biographer on the market by next summer. It will be available in drugstores, by prescription only, and should sell for about $400.

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