1. Kupecz, Deb NP, PhD

Article Content

The GlucoWatch G2 Biographer is a wristwatch-like device that noninvasively and continuously measures blood glucose through the skin. The device is approved for use in adults and children (ages 7-17) with diabetes to supplement finger stick measurements in detecting and tracking patterns in glucose levels.


The device is not to be used as a substitute for finger stick measurements. The GlucoWatch G2 Biographer is available by prescription only.


The Biographer uses reverse iontophoresis to continuously measure blood glucose through the skin. The Biographer has a built-in alert system that can sound an alarm if glucose readings are high, low, or likely to be low within the next 20 minutes. It automatically creates an electronic "diary" that can store more than 8,500 readings in its memory.


The device consists of the durable Biographer, worn on the wrist, and the AutoSensor, a disposable component attached to the back of the device. The AutoSensor must be replaced each time the Biographer is worn. After a new AutoSensor is inserted into the Biographer, a 2-hour warm-up period is required before readings can be taken. After the warm-up is completed, the device is calibrated by doing a finger stick blood glucose test and entering the results into the Biographer.


After calibration, the device reads glucose levels every 10 minutes for 13 hours. Each Biographer reading corresponds to blood glucose values from about 15 minutes earlier.


The low-level electric current used by the Biographer to read blood glucose levels may cause skin irritation after use. Patients should change the location of where they wear the Biographer for each use. Symptoms should disappear within a few days if the user does not put the Biographer back on the same place on the arm.


The GlucoWatch G2 Biographer was developed by Cygnus (Redwood City, Calif.) and is marketed by Sankyo Pharma (New York, NY). The Patient Starter Kit, which includes the Biographer, battery charger and batteries, two watchbands, logbook, and instructional materials, costs $698. The Kit does not include the AutoSensors ($7.50 each), which are sold separately and require refrigeration. The Analyzer software with a download terminal is available for $60 if purchased within 90 days of the Starter Kit.


For more information, visit or call (866) GLWATCH.


Clinician Critique

The GlucoWatch G2 Biographer is the first FDA-approved meter that tests glucose levels noninvasively. It is intended for detecting trends and tracking patterns in glucose levels and does not replace conventional finger stick testing.


The device, which uses a technique called reverse iontophoresis to extract fluid through the skin, measures the glucose in the fluid. Following a 2-hour warm-up period, a finger stick glucose measurement must be entered into the device for calibration. It is then capable of providing up to 6 glucose readings per hour for 13 hours.


In clinical studies, individual GlucoWatch values were shown to differ from finger stick measurements up to 25% of the time in unpredictable patterns, so individual readings cannot be used to adjust therapy. GlucoWatch measurements were consistent with traditional finger stick measurements 75% to 90% of the time with a range between 40 mg/dL and 400 mg/dL. A recent study in children demonstrated a decreased incidence of hypoglycemic events and lower glycosylated hemoglobin levels. However, problems with consistent operation occur when there are changes in room temperature, if the device is bumped unexpectedly, and when users perspire excessively. About 50% of users experience transient skin irritation.


The watch costs almost $700; AutoSensors are sold in cartons of 16 for $120. The annual cost for AutoSensors would be approximately $5,000 if used continuously. It is not clear if these costs will be covered by traditional insurance plans.


Although the GlucoWatch offers a painless method of glucose testing, a strong patient education program is necessary to ensure correct use and data interpretation. The clinician must assess the patient's and family's ability to use and afford this device.