By: Daniel Trecroci
Cygnus, Inc. of Redwood City, California, has finally completed its long journey to receiving FDA approval for its GlucoWatch Biographer. People with diabetes, however, should expect to wait until the end of 2001, or later, before being able to purchase one.
The Food and Drug Administration, in a March 22 press release, announced that the GlucoWatch Biographer was granted clearance “for use along with, not as a replacement for, finger-prick blood tests to monitor glucose.” According to Craig Carlson, vice president of finance at Cygnus, the GlucoWatch Biographer will not be available on retail shelves or in doctor’s offices, but through a direct-to-consumer model.
“Consumers will call a toll free number, provide their prescription, take a little quiz where they answer some basic questions and then pay with their credit card,” says Carlson. “Then our distribution partner, Livingston Healthcare, will ship the product directly to their home.”
Carlson anticipates approximately two million prospective users will want a GlucoWatch Biographer.
‘One of the First Steps’ in Eliminating the Need for Finger-stick Tests
Tommy Thompson, secretary of health and human services, said of the GlucoWatch approval, “Today’s action heralds the advent of new technologies that promise dramatic improvements in the quality of life for the millions of Americans who have diabetes.”
Bernard Schwetz, the FDA’s acting principal deputy commissioner, said, “The GlucoWatch is one of the first steps in developing new products that may one day completely eliminate the need for daily finger-prick tests.”
Nancy Bohannon, MD, an endocrinologist at Monteagle Medical Center in San Francisco, says the approval of the GlucoWatch Biographer is a “huge step in the direction we’ve been trying to go for the last 25 years.”
Bohannon adds that the approval news is also encouraging in light of recent reports indicating that after-meal blood-sugar spikes are even more closely correlated with diabetic complications.
“By having glucose values automatically determined by the Glucowatch every 20 minutes and without having to stop whatever one is doing to test at each time, the person will be able to adjust insulin doses before meals to decrease the spikes and achieve better control,” Bohannon said.
In a Cygnus press release, John C. Hodgman, chairman, CEO and president of Cygnus, said, says Cygnus’s next step prior to a “broad launch” in the United States will include a pilot marketing program and the finalization of large-scale manufacturing capabilities to meet projected demand.
Measures Glucose from Interstitial Fluid
The GlucoWatch Biographer uses technology that has never been available before. It is non-invasive and does not measure glucose from the blood.
Following a three-hour warm up period, the GlucoWatch Biographer collects glucose from interstitial fluid, which is the clear fluid just underneath the surface of the skin.
The GlucoWatch Biographer measures and displays glucose levels automatically—as often as every 20 minutes—for up to 12 hours. It also creates an “electronic diary,” storing up to 4,000 BG readings that can be reviewed at the touch of a button. Cygnus says this helps detect trends and track patterns in BG levels.
Alarm Alerts Users to Lows
GlucoWatch Biographer users can also set personal glucose-alert levels so that an alarm sounds if readings are too high or low, or if readings decline rapidly.
In its January 2000 issue (“FDA Panel Backs GlucoWatch Monitor,” p.15) DIABETES HEALTH reported that data submitted before a December 1999 FDA advisory panel explained that when the GlucoWatch alarm was set at 90 mg/dl, only 62 percent of hypos were foretold. In addition, when the GlucoWatch monitor’s alarm was set at 100 mg/dl, 75 percent of hypos were foretold, and when it was set at 110 mg/dl, 86 percent of hypos were foretold.
Russell Potts, MD, vice president of research at Cygnus recommends the GlucoWatch alarm be set at 90 mg/dl to be sure your are notified if you go below 70 mg/dl.
“You would set it at 20 mg/dl before your target value so that it gives you an early warning,” says Potts. In a January 2000 interview with DIABETES HEALTH Potts said, “Sometimes this means that the alarm will sound if you are not having a hypo, but it’s better to be safe.”
In addition to the alarm function, Carlson touts the GlucoWatch Biographer’s electronic diary.
“Because of the frequent measurements, you can scroll back and see in previous readings that you have gone from 200 to 100 in a hurry,” says Carlson. “This is the true value of this type of device—the trend data. You can imagine that if your last five readings were showing a precipitous decline it might lead you to a different behavior.”
How Reliable is it?
In its March 22 press release, the FDA said that GlucoWatch BG results differed by more than 30 percent up to 25 percent of the time. Jane Seley, RN, CDE, MPH, MSN, GNP, a doctoral candidate at New York University, says a 30-percent range of error 25 percent of the time is “clinically significant and practically worthless.”
The FDA adds that the GlucoWatch “sometimes gave erroneous readings [and] was less effective at detecting very low blood sugars than very high levels. Seley adds, “Where is the value of using this to detect low BGs early when it is less likely to give you an accurate reading at lower levels?”
A 20-minute Lag
In a study published in the October 1999 issue of Diabetes Care, Satish K. Garg, MD, evaluated the accuracy of the GlucoWatch Biographer in comparison with the HemoCue blood glucose analyzer and a One Touch Profile meter. Twenty-eight type 1s were evaluated in a clinical setting and at home. The subjects wore the monitor 15 hours per day for three consecutive days. The GlucoWatch performed well at both the high level (240 mg/dl) and the low level (70 mg/dl), as well as all points in between.
Garg noted there was a 20-minute lag between the GlucoWatch and the blood glucose meters. Potts confirms that the 20-minute lag is still relevant. He says, however, even if a person with diabetes saw what their blood sugars were 20 minutes ago, they can still have an idea of where their BGs are headed.
“You can figure out very quickly if you are going south by looking at the data from measurements 60, 40 and 20 minutes ago,” says Potts.
Garg also noted that rapid temperature changes, excessive sweat, electrical noise, high background currents and open and short circuits can cause the GlucoWatch to “skip” tests. Potts says this is no different than what a LifeScan One Touch meter does.
“If you look at a One Touch user’s manual, it says if you put too small a drop of blood, or operate with too much ambient light, or you go outside on a very hot day, it will not give a reading,” says Potts. “It says it will display an ‘error code.’ The GlucoWatch does the same thing. There are predetermined conditions under which it will not provide reliable measurements. All BG meters do this.”
DIABETES HEALTH patient-advocate advisor Joan Hoover of Chevy Chase, Maryland, says a sweaty arm and body are classic signs of a low blood sugar, suggesting that the GlucoWatch Biographer might not be very helpful. Potts says the GlucoWatch has audible perspiration and hypoglycemia alerts. In fact, the same alert goes off for both.
“If this alert goes off, the patient has to say, ‘Gee my last measurement was 150 and the one before that was 200, I just took insulin and forgot to have lunch,’ or ‘I’m actually perspiring, my last measurement was 100, the one before that was 105, I haven’t had insulin and I just ate lunch,'” says Potts. “By sounding the alert, you provide the person with the opportunity to think about what the circumstances are, and it may or may not be a hypo, but we always provide the alert. Perspiration and hypos are often correlated. Because of that, we set off the alert when you are perspiring.”
Side effects of the GlucoWatch monitor include mild skin irritation, edema (accumulation of fluid), and erythema (redness of the skin) that, in clinical studies, went away after the GlucoWatch was removed.
Carlson says Cygnus is still finalizing what the pricing for the GlucoWatch Biographer will be. He tells DIABETES HEALTH that Cygnus is thinking it will be somewhere in the $350 to $450 range, but wishes to qualify that this is not “set in stone.” The disposable sensor pads will cost between $4 and $5 apiece. Each sensor pad lasts for 12 hours.
Additional information about the GlucoWatch Biographer can be obtained by calling the company’s toll free number, (866) 459-2824, or by visiting www.glucowatch.com.