FDA Panel Backs GlucoWatch Monitor

An advisory panel of the U.S. Food and Drug Administration (FDA) unanimously recommended approval of the GlucoWatch monitor on December 6, 1999. The advisory panel, which approved the GlucoWatch monitor with conditions, said that the monitor could offer a tremendous benefit by measuring glucose far more often than blood tests can.

“This is quite a device,” said FDA adviser Dr. Stephen Clement of Georgetown University Medical Center, “a huge undertaking.”

The FDA is not bound by its advisers’ recommendations but typically follows them.

Final FDA Approval

Spokespersons at Cygnus, Inc. of Redwood City, California, the company that manufactures the GlucoWatch monitor, say that they are looking at MiniMed’s continuous glucose model in determining when the GlucoWatch may get final FDA approval.

“It took them approximately four months from the time of the advisory panel’s recommendation,” says Craig Carlson, senior vice-president of finance and chief financial officer at Cygnus. “We just assume that we will be on a similar timeline.”

Carlson anticipates a possible FDA ruling by the end of March. From that point, Cygnus would need to get a marketing collaboration in place. Then, the GlucoWatch can go on the market.

“Roughly speaking, this product could be on the market by about the middle of the year,” he says, “maybe a little bit into the third quarter.”


The conditions laid out by the FDA Advisory Committee were:

  1. an education program
  2. label revisions, and
  3. a post-market study of detection of hypoglycemia and hyperglycemia.

In a December 7, 1999 conference call, John C. Hodgman, chairman, president and chief executive officer of Cygnus, called these conditions “very manageable.”

Glucose Readings From Interstitial Fluid

The GlucoWatch monitor, which will be available only by prescription, is intended for use by adults, 18 years and older, who have diabetes. It is intended for use at home and in health care facilities. Following a three-hour warm-up period, the GlucoWatch monitor could provide painless, noninvasive measurements of blood sugar every 20 minutes for up to 12 hours.

The monitor works by sending a tiny electric current through the skin. It measures glucose from the interstitial fluid just underneath the surface of the skin. The GlucoWatch has the capability to alert users when glucose levels are too high or too low, even while they sleep. These situations are hard to identify with traditional glucose testing.

A Supplement to Fingerstick Testing

Cygnus and the FDA advisers agreed that patients should never decide to use insulin based on a GlucoWatch measurements without first doing a fingerstick test. Cygnus officials say that the true benefit of the GlucoWatch is that it allows the person with diabetes to see “trends and patterns” in their BG management.

“The GlucoWatch is not meant to replace fingersticks,” says Carlson. “We proposed to the FDA that it be used to supplement, rather than replace fingersticks. The physicians will have to develop individual usage recommendations for their patients because peoples’ bodies are different.”

Similar in Accuracy to Fingerstick Tests

In a recent study that was published in the October 1999 issue of Diabetes Care, the GlucoWatch monitor compared well with blood sugar measurements obtained using a HemoCue blood glucose analyzer and a One Touch Profile meter. Twenty-eight type 1s were evaluated in a clinical setting and at home. The GlucoWatch monitor performed well at both the high level (240 mg/dl) and the low level (70 mg/dl), as well as all points in between.

Researchers noted, however, that there was a 20-minute lag between the GlucoWatch monitor and the blood glucose meters. Also, it was noted that rapid temperature changes, excessive sweat, electrical noise, high background currents, and open and short circuits can cause the GlucoWatch monitor to “skip” tests. In the home tests, 26 percent of all tests were skipped. The FDA advisers stress that the GlucoWatch monitor is less effective at detecting life-threatening low blood sugar than at spotting dangerous high blood glucose levels.

Side effects of the GlucoWatch monitor include mild skin irritation, edema (accumulation of fluid), and erythema (redness of the skin) that went away after the GlucoWatch monitor was removed.

Accuracy in Reading Low Blood Sugars

FDA officials warned that 25 percent of the time, GlucoWatch readings can differ from blood tests by about 30 percent. For example, if the GlucoWatch reads a glucose level of 150 mg/dl, the actual blood sugar level might be anywhere from 135 to 165 mg/dl. FDA officials think this might be a problem when it comes to detecting hypoglycemia or blood sugar that drops below 70 mg/dl. Cygnus emphasizes, however, that the GlucoWatch can be programmed to sound an alarm well before glucose levels drop that low, giving the patient time to do a finger stick to verify the real level.

According to data submitted before the FDA panel, studies found that when the GlucoWatch alarm was set at 90 mg/dl, only 62 percent of hypos were foretold. In addition, when the GlucoWatch monitor 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 that the GlucoWatch be set at 90 to 100 mg/dl to detect a reading of 70 mg/dl.

“Sometimes this means that the alarm will sound if you are not having a hypo, but it’s better to be safe,” says Potts.

Usage Situations

Officials at Cygnus told the FDA panel that the GlucoWatch monitor may be used in the following situations:

  1. routine use, i.e., every day
  2. periodic use, i.e., nighttime only or on weekends
  3. situational use, i.e., sick days or hospital admission, and
  4. educational use, i.e., to see how dietary changes affect blood sugar.

Stock Nearly Doubled

Cygnus stock was valued at $9.25 per share on December 3, 1999. On the first day of trading after the December 7 FDA announcement, it increased $8.75 to $18 per share. At press time, it was valued at $18.25 per share.

Cygnus recently announced it would sell most of the assets from its drug delivery business to a Johnson & Johnson unit and focus on developing the GlucoWatch. Cygnus is currently seeking an alliance for the commercialization of the GlucoWatch monitor worldwide (except Japan and Korea) which would include distribution, sales, marketing, and customer service support.

Tokyo-based Yamanouchi Pharmaceutical Co., Ltd., a significant participant in the Japanese pharmaceutical market, has marketing and distribution rights for the GlucoWatch monitor in Japan and Korea.


Carlson says that the GlucoWatch itself will cost between $250 to $350, and the disposable sensor pads will cost between $4 and $5 apiece. Each sensor pad lasts for 12 hours.

For more information, contact Cygnus at 650-369-4300, or check out their Web site at www.cygn.com.

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