Poster
Evaluation of the GlucoWatch biographer: an automatic and
non-invasive glucose monitor
Janet Tamada¹, Lois Jovanovic², Satish Garg³, Neil
Ackerman¹, Steven Fermi¹, Russell Potts¹, Michael Tierne¹ ¹Cygnus, Inc.,
Redwood City, CA, USA; ²Sansum Medical Research Institute, Santa
Barbara, CA, USA; ³Barbara Davis Center for Childhood Diseases,
University of Colorado Health Sciences Center, Denver, CO, USA
Background
The GlucoWatch® biographer is designed to facilitate the acceptance and
success of intensive diabetes management by providing frequent,
automatic glucose readings. The GlucoWatch biographer is worn on the arm
like a watch. Glucose is sampled through skin by application of a
low-level electric current, a process known as reverse iontophoresis,
and the extracted glucose is measured with an electrochemical biosensor.
The biographer displays up to three readings per hour for as long as 12
hours, following a single glucose measurement taken with a traditional
blood glucose meter three hours after application. The biographer
features user-adjustable high and low alert settings to warn of
potential hypo- or hyperglycemia and stores 4000 readings, which can
provide long-term glycemic pattern data. Data integrity checks screen
for potentially erroneous data and the biographer displays a “skip”
message to the user instead of a measurement.
Objective
The objective of this clinical study was to assess the performance of
the GlucoWatch biographer in a demographically diverse diabetic
population in a variety of environmental settings.
Methods
The accuracy of the biographer vs serial blood glucose measurements was
studied in diabetic subjects in a controlled clinic environment, a
simulated home environment, and the home environment. The subject
population consisted of over 400 adult subjects diagnosed with Type 1 or
Type 2 diabetes who required insulin treatment. Performance was assessed
by analyzing paired glucose readings between the biographer and a
traditional blood glucose meter. A number of blood glucose meters for
both calibration and comparative blood measurements were utilized. Over
1000 biographer uses and 14,000 paired glucose measurements were
studied.
Results
Time profiles over 12 hours of measurement show close tracking of the
biographer results with fingerstick blood glucose measurements. The
figure shows a sample plot. The mean difference (MD) between the two
measurements is less than 5 mg/dl over all studies. The mean absolute
value of the relative difference (MARD) is approximately 20%. Over 94%
of the data was in the clinically acceptable Error Grid A and B zones.
Overall performance was comparable in all environments as shown in the
Table.
Conclusions
The GlucoWatch biographer provides frequent measurements of glucose over
a 12-hour period with good clinical accuracy. It can detect trends and
track patterns in glucose levels in diabetic subjects with diverse
demographic characteristics. The GlucoWatch biographer should facilitate
improved diabetes management by the diabetic patient and caregiver.
