The Food and Drug Administration has approved a wristwatch-like device that provides more information for managing diabetes. It is intended for use along with, not as a replacement for, fingerstick blood tests to monitor glucose, in order to ensure accurate results.

The GlucoWatch Biographer extracts fluid through the skin by sending out tiny electric currents. The watch may be worn for 12 consecutive hours, producing 3 measurements every hour, even while asleep. An alarm will sound if blood glucose levels are detected to be dangerously low, or if a measurement was skipped, as can occur in the presence of excessive sweat.

The device is available only by prescription to detect trends and track patterns in glucose levels in adults age 18 and older. It is manufactured by Cygnus, Inc.

Clinical studies conducted by the manufacturer showed that GlucoWatch measurements generally were consistent with the results from traditional fingerstick blood tests. However, up to 25 percent of the time, the results differed by more than 30 percent. The GlucoWatch sometimes gave erroneous readings, was less effective at detecting very low glucose levels than very high levels, and would not measure it at all if a patient's arm was too sweaty. The GlucoWatch also caused mild to moderate skin irritation in at least half of the patients.

The FDA warns that, because of the potential for error, physicians and patients should never use an individual GlucoWatch reading alone to make changes in insulin doses. Instead, the GlucoWatch results should be interpreted with several sequential readings over time and then confirmed with a fingerstick test.

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