New monitoring device helps diabetics
The U.S. Food and Drug Administration has approved the GlucoWatch Automatic Glucose Biographer (by Cygnus), a noninvasive glucose-monitoring device that fits like a wristwatch. The monitor is indicated to detect trends and track patterns in blood glucose levels of diabetics 18 years and older. It is the first and only monitoring system that provides glucose readings automatically and noninvasively, up to three times an hour, for twelve hours at a time, day or night. The device is available only by prescription and is intended as an adjunct to standard blood glucose meters.
The tool is an important new technology for people with diabetes who may benefit from having more information about their glucose levels. Experts agree that many people with diabetes should test their glucose levels as often as four to seven times a day. However, because of the pain and inconvenience of current testing methods, many people with diabetes perform just a few tests each day, often right before meals. This means they may miss revealing information about glucose levels at other important times, such as after meals or during sleep. With the GlucoWatch Biographer, people with diabetes will have access to the type of information that may help them make better-informed decisions about diet, medication, and physical activities. This may eventually lead to a higher quality of life and lower health care costs.
The system consists of two integrated parts, the Biographer and the AutoSensor. The Biographer is worn like a watch and calculates, displays, and stores glucose readings. The AutoSensor is a single-use component that first collects and then measures the glucose sample. The AutoSensor snaps into the back of the Biographer and adheres to the skin, providing up to 12 hours of automatic readings.
AutoSensor works by reverse ionophoresis
The AutoSensor measures glucose collected through the skin, rather than through the blood. As the device directs a low electric current, positive and negative ions pull dissolved glucose through the skin to two gel collection disks at the anode and cathode of the sensor, where the glucose molecules react with glucose oxidase to form hydrogen peroxide. A biosensor in contact with each disk detects the hydrogen peroxide and generates an electronic signal that is then converted into a glucose measurement.
The Biographer can provide supplemental information about glucose changes over the course of a single day or night, over a period of several days or weeks, or on a more routine, daily basis. The Biographer enables patients and their health care providers to see trends and patterns in glucose levels that might not be detected with conventional finger-stick monitoring alone. Health care providers can make treatment decisions with the advantage of having more long-term, continuous glucose data available, in addition to periodic information. The glucose readings are stored in memory in the Biographer and can be viewed at any time at the touch of a button.
As patients plan a schedule for wearing the GlucoWatch, pharmacists should be sure to emphasize the circumstances in which patients should obtain a finger-stick test using a blood glucose meter. These situations include times when the patient must calibrate the Biographer, when patient symptoms do not match Biographer readings, or when the patient is considering making immediate changes in daily therapy or taking an insulin injection. In these instances, Biographer results should not be the only source of information for making decisions.
In all related clinical studies, the Biographer readings closely matched the direction and speed of changes reflected in the blood glucose data. In each study, the median correlation coefficient was approximately 0.90. Based on results of clinical findings, the manufacturer of the device recommends setting the low-glucose alert at 20-30 mg/dL above the desired level of low blood glucose detection. In the same way, the high-glucose alert should be set lower than the level of desired detection.
Before using the new device, patients must complete a training program provided by the manufacturer. The more pharmacists are familiar with the device themselves, the better they will be able to assist patients in the use of this device. The data collected by the Biographer can be transformed by pharmacists into useful information to help diabetic patients adjust monitoring, diet, exercise, and medication regimens.
For more information about the GlucoWatch Biographer and to see a picture of the device, visit the GlucoWatch Web site at www.glucowatch.com/.
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