It is one of the most painful and inconvenient tasks for those suffering from diabetes: frequent finger pricks to check blood sugar levels. As a result, many patients draw blood once daily, on average, not the four to seven times a day suggested by doctors.
But a wristwatchlike device soon may provide diabetics in the United States with a pain-free and automatic way to monitor glucose. The device, called the GlucoWatch Biographer, checks sugar levels every 20 minutes by sending tiny electric currents through the skin.
The Food and Drug Administration approved the device in March for use by adult diabetics. The manufacturer, Cygnus of Redwood City, Calif., is waiting for manufacturing approval by the federal agency so it can start mass-producing the watch, which could go on the market by the end of the year. It already is available in Britain.
Company officials said the watch probably would cost $400 to $500 and the disposable sensors used with it, $4 to $5 each.
About 16-million Americans have diabetes, which occurs when the body cannot produce insulin or use it properly and thus cannot regulate the level of sugar in the blood. When not treated properly, diabetes can lead to heart disease, stroke, blindness and kidney disease.
The GlucoWatch Biographer, however, will not completely replace the finger prick. First, the FDA emphasized that the watch should supplement traditional blood tests because it sometimes provided erroneous readings. Second, the user must calibrate the watch each time he puts it on by drawing blood from his finger, measuring the glucose level with a regular meter and entering the result into the watch.
Still, patients who used the watch during clinical trials said the device helped keep them healthy by providing more frequent updates on their blood sugar levels. The most useful feature, they said, is an alarm that sounds if their sugar levels are too high or too low or if the readings rapidly decline.
The watch face displays the time and the user's most recent blood sugar level. (It stores up to 4,000 readings). A small arrow indicates whether the current level is higher or lower than the last, and another icon shows the time remaining until the next reading.
Dr. Steven V. Edelman, a tester, said the watch revealed that his blood sugar fell considerably while he slept. It also showed that his levels immediately dipped after large meals but then quickly rose.
"Traditional blood sugar tests provided me with only one point in time," said Edelman, an associate professor of medicine at the University of California at San Diego. "With the watch, I can follow my levels every 20 minutes if I want, or scroll back to see my history over the past few hours."
Edelman said he used the device two or three times a week, particularly on days "when I'm running around like a mad man and should be watching myself."
Users slide a thin plastic sensor onto the back of the watch each time they put it on. After a three-hour warm-up, the watch begins extracting glucose from fluid in skin cells, displaying a readout every 20 minutes for a 12-hour period.
"Clearly, it's not a Rolex," said Russell Potts, vice president for research and development at Cygnus. "This is the Model T, and there is lots of room for improvement. We're trying to make this into the Ferrari."
The next model of the GlucoWatch Biographer will reduce the warm-up period to two hours, increase the number of readings per hour from three to six and lengthen the monitoring period to 13 hours, said John Hodgman, chairman, chief executive and president of Cygnus. It is in development and no release date has been set.
Although the FDA mandated that the device be used in conjunction with the finger pricks, Lois Jovanovic, an early watch user from Santa Barbara, Calif., said she was confident that the numbers from a finger test and the watch were close enough for her needs. "It clearly tells me the difference between too low, just right, high and super high," she said. "Say I got a super-high reading; I would test myself anyway."
How frequently users will wear the watch probably will depend on how they manage the disease now, Potts said. Those who frequently test their blood are likely to be early adopters of the watch and wear it often, he said, but others may only use it when they travel or are having a stressful day.
The device will be available by prescription to diabetics 18 and older, but many doctors hope the FDA will approve it for use by children.
Researchers do not know whether skin cell fluid measurements of glucose levels are as comparable to blood measurements in children as they are with adults, but results from a pilot study presented last month at a meeting of the American Diabetes Association showed that the watch performed similarly for diabetic children ages 7 to 17 and for adults.