MANY diabetics have to endure frequent, painful finger pricks to monitor
their blood sugar levels. But soon just a single prick of the finger will be
enough to calibrate a watch-like monitor that can measure blood sugar levels
non-invasively throughout the day.
Called the GlucoWatch, the $300 device, which is close to achieving
final approval by the US Food and Drug Administration, could be in production by
the end of this year. Diabetes experts believe the watch will revolutionise the
prospects for diabetics. Frequent blood sugar monitoring helps detect the
excessively high or low blood sugar levels that lead to complications such as
blindness, kidney failure and nerve damage. But many diabetics find it painful
and inconvenient to check their blood sugar more than once or twice a day, so
they are unaware of when they could be in danger.
The GlucoWatch, which was developed by Cygnus of Redwood City, California,
sits on top of a disposable gel disc that contains the same enzyme used to
measure glucose levels in home monitors. Instead of testing the blood directly,
the watch draws glucose from the body into the disc using a tiny electric
current flowing between two terminals beneath the watch body. As the current
passes through the skin, charged molecules migrate towards the electrodes
(see Diagram).
Glucose molecules, although uncharged, get swept up by this ion flow
and are dragged across the skin to the gel disc by the cathode.
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After putting on the GlucoWatch you have to wait for three hours while a new
gel pad hydrates and reaches equilibrium with the skin. After this 鈥渨arm-up鈥�
period, you calibrate the device using a glucose level taken from a standard
finger-prick test. After that, the watch measures glucose levels every 20
minutes for a 12-hour period. If levels go too low or too high, it sounds a
warning beep.
鈥淚t鈥檚 data that鈥檚 never been available before,鈥� says Steven Edelman, a
diabetes specialist at the School of Medicine at the University of California,
San Diego. Edelman, a diabetic who has worn the GlucoWatch several times, says
continuous monitoring revealed that his blood levels fell dangerously low at
night while he slept. 鈥淚 really learned a tremendous amount,鈥� he says.
Cygnus expects the FDA to approve the GlucoWatch as a supplement to current
monitoring methods, and to advise users to perform a traditional finger-prick
test before injecting insulin. Satish Garg of the University of Colorado Health
Sciences Center in Denver says: 鈥淭hat鈥檚 not real life.鈥� He worries that
diabetics will base their insulin dose on the GlucoWatch alone.
Garg also fears that doctors may provide it to young children with diabetes,
even though it has only been tested in adults. 鈥淭his is a major concern,鈥� agrees
Cygnus vice-president Neil Ackerman, who says the company wants to test the
device in children as quickly as possible.