The US Food and Drug Administration has approved a wristwatch-like device that is said to provide adult diabetics with more information for managing their condition. It has been designed for use along side, and not a replacement for, finger-prick blood tests to monitor glucose.
The GlucoWatch Biographer, made by Cygnus, is said to extract fluid through the skin by sending out tiny electric currents. Glucose levels are measured using this fluid every 20 minutes for 12 hours, even during sleep.
The glucose molecules react with glucose oxidase to form hydrogen peroxide. This reaction is said to produce an electrochemical signal that is measured by an AutoSensor
The Biographer uses a patient’s finger-stick calibration value (entered at the beginning of the 12-hour monitoring period) to convert the signal into a glucose reading and the device sounds an alarm if patient’s glucose reaches dangerous levels.
Currently the GlucoWatch measurements must be used along with finger pricks to ensure accurate results.
Clinical studies conducted by Cygnus showed that GlucoWatch measurements were consistent with the results from traditional finger-prick 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 50 percent of patients.
The device was studied in adults 18 and older in both clinical and home settings. The studies generated 19,000 glucose readings from 1,400 devices over 25,000 hours of use.
Cygnus warn that because of the potential for error, physicians and patients should never use an individual GlucoWatch reading alone to make changes in insulin doses.