Finally Something Noninvasive

The race is on! Since 1986, the contestants—more than 100 start-up biotech companies—have been competing for the prize: a chunk of the billion-dollar market that awaits the manufacturer of a reliable, FDA-approved, noninvasive glucose monitor.

Business people, engineers, scientists and physicians have collaborated to devise a better and less painful way for people to test blood glucose and manage their diabetes.

“A noninvasive device that’s reliable, accurate, user-friendly, and not sensitive to environmental stresses would be a miracle,” says Stephen Clement, MD, director of Georgetown University Medical Center’s diabetes center and chair of the FDA Clinical Chemistry and Clinical Toxicology Devices Panel. “It will help patients make critical decisions in the moment, such as whether it’s safe to exercise or drive a car.”

The Rise and Fall of the GlucoWatch

In 2002, Cygnus Inc. of Redwood City, California, jumped to the head of the competition with its GlucoWatch G2 Biographer. However, the device is not considered truly noninvasive because a low electric current actually pulls glucose containing interstitial fluid through the skin. In addition, patients using it often developed skin irritations.

So the search for the “holy grail” of diabetes self-management resumed.

Although the timeline for the availability of noninvasive meters is generally measured in years rather than months, several prototypes are now in the pipeline.

How Will We Know It’s Noninvasive?

No one knows exactly what the first marketable noninvasive monitor will look like, but David Klonoff, MD, director of the Mills-Peninsula Diabetes Research Institute in San Mateo, California, knows what it won’t do.

It will not “harvest body fluids” such as blood, interstitial fluid and skin cells by means of fingersticking or any other penetrating method, such as the implantation of a sensor under the skin.

To produce prototypes, researchers have had to invent new technologies. Most techniques shine beams of light on a person’s wrist or another site. Blood glucose is measured by calculating the absorption, scattering or refraction of light waves.

Take, for example, the technique of infrared spectroscopy—a harmless beam of light passes through the finger. The molecules in the finger absorb a specific and unique number of light waves. (Experts compare this measure of absorption to a person’s signature or fingerprints.) The infrared technology separates the glucose molecules and calculates the measurement mathematically.

Other technologies use radio waves, ultrasound or another energy source instead of light.

Eight to Keep Your Eye On

Diabetes Health has singled out eight noninvasive prototypes in various stages of development.

All of these prototypes must meet FDA standards before they can be marketed. The FDA considers these devices to fall into a “high risk” category, and, as a result, requires both analytical and clinical studies. In other words, manufacturers must prove their device gives accurate and consistent measurements.

The prototypes also must meet certain performance criteria during human trials. For instance, glucose meters must be as accurate as fingerstick methods, which fall in a range of plus-or-minus 20 percent. They must store test results and recognize emergency situations (such as low or high blood glucose).

The current prototypes work quickly, anywhere from a few seconds to 30 seconds. As for cost, many “insurance companies probably will cover noninvasive calibrated meters to avoid paying for five to seven strip tests a day,” says Davida Kruger, MSN, RN, CDE, of Detroit.

But many unanswered questions remain, and companies often supply more hype than data.

Satish Garg, MD, director of the young adult clinic at the Barbara Davis Center for Childhood Diabetes at the University of Colorado Health Sciences Center, does not feel that a noninvasive meter is right around the corner. He says that the problem of recalibrations still persists, and that companies struggle with correlations (with capillary blood glucose results obtained by fingersticking).

“The FDA needs to shift the paradigm of glucose monitoring away from ‘correlations’ to ‘trends,’ ” says Garg. “We need to crawl before we run.”

Pendra Takes the Lead

According to Garg, the meter with the best chance of making it to the U.S. market in the next two years is the Pendra by Pendragon Medical.

In May 2003, the watch-like device received a CE certificate-European authorization comparable to FDA approval in the United States.

The Pendra uses radio-wave impedance to measure glucose and can take up to four readings per minute. In addition, it warns patients of high and low glucose levels, shows “sufficient accuracy” (according to the company’s Web site) and detects trends.

However, the Pendra is designed as a supplementary device to standard blood glucose meters.

Sensys Glucose Tracking System

Larger than the Pendra, the Sensys Glucose Tracking System (GTS) resembles a personal digital assistant.

Sensys Medical (formerly Instrumentation Metrics) has received approval for investigational use from the FDA, but the company expects the professional device to be on the market in 2004. The home device is scheduled for 2005.

The Sensys GTS uses near-infrared (NIR) spectroscopy technology-specifically, diffuse reflectance NIR. When a fiber optic probe is placed over a person’s forearm, light shines into the skin. (The probe was designed to be sensitive to skin texture and temperature changes, since these variables impact the reflected light.) A computer chip in the handheld device analyzes the reflected light, and the glucose level is displayed on a digital screen.

Two trials of 140 people with diabetes each showed the Sensys GTS was accurate in 90 percent of patients studied.

Stephen Monfre, chief operating officer of Sensys Medical, says the Sensys prototype is as accurate as fingerstick methods 75 to 80 percent of the time.

Glucon Solution

Glucon, an Israeli-based company, also boasts of its noninvasive model’s accuracy.

Glucon has tested more than 50 patients and says the results compare well with conventional fingerstick methods. Touting a “breakthrough” photoacoustic (optical and sound-based) technology that figures glucose levels from inside blood vessels, Ron Nagar, Glucon’s president and CEO, says their technology is more precise than measuring glucose in interstitial fluid.

“There’s a time lag between the interstitial measure and the blood glucose measure,” Nagar recently told Glucon’s technology also compensates for variables, such as urea, lipids and bilirubin, which can interfere with blood glucose readings.

Nagar says Glucon will begin “definitive” clinical trials for FDA approval in 2005. By 2006, the company expects to launch its product in the United States, where it will set up regional headquarters.

The company got a recent infusion of $13 million from investors in Israel and Japan.


Although Glucon measures glucose through the blood vessels in the wrist, LifeTrac Systems Inc. uses NIR technology on the earlobe.

According to LifeTrac CEO William Danton, clinical trials at Brigham Women’s Hospital in Cambridge, Massachusetts, verified the SugarTrac Noninvasive Glucose Monitor’s accuracy to be within 5 percent when compared to fingerstick tests.

However, a recent statement from Ronald A. Arky, MD, LifeTrac’s consultant and chief of the diabetes and metabolism department at Brigham and Women’s Hospital, sounds a sour note on the future of SugarTrac. According to Arky, “No progress has been made in overcoming the mechanical difficulties the designers encountered this past year.”


CME Telemetrix may be facing similar hurdles.

The company’s Web site makes clear it has a way to go before seeking FDA approval.

For one thing, CEO Duncan MacIntyre recently announced a movement to “replenish cash reserves.” CME needs a bankable partner if it is to produce and market the GlucoNIR, a device that uses infrared light to measure glucose.


MedOptix also needs further financial support.

However, its prototype, ReSense, has been tested in many California locations.

Company president Robert Blair, formerly a physicist in the semi-conductor industry, wants a piece of the noninvasive pie, but his motivation is much more personal: his son, Jason, developed diabetes more than a decade ago. This led Blair to form a partnership with Herb Berman, a physicist with experience in infrared devices, and retired doctor Carl Levinson. The three founded MedOptix in 1999.

“Mid-infrared ray technology (which MedOptix uses) is better than NIR,” claims Blair, whose prototype employs a reflective sensing technique from the skin-a technique he says is different from any other technology because the skin is relatively free of water, Blair says. “It’s easier to analyze than blood, which is mostly composed of water, since water interferes with glucose measurement.”

According to Blair, the earliest that the company would apply for FDA approval is 2005.

Home Glucose Measurement

Magneto-wave spectroscopy is Pindi Products’ patented technology.

According to Pindi, company president Milton E. Fuller has devised a way to receive wave signals inside a magnetic field. The computer of the prototype receives the signals (which are specific to certain human body fluids and proteins) and interprets them, relaying the “glucose” information within seconds.

Head-Mounted Goggles

Even NASA has joined the noninvasive race.

Astronauts, not just people with diabetes, need noninvasive monitoring, too. Which is why NASA has developed optoelectronic technology.

“Blood glucose determination is the most basic parameter for human health,” says Rafat R. Ansari, a biomedical engineer at Glen Research Center in Cleveland, Ohio. “Body physiology can change due to exposure to zero gravity, especially in long-duration missions, for example, to Mars.”

NASA’s prototype uses seven optical techniques, including dynamic light scattering, spectroscopy and autofluorescence.

Resembling night-vision goggles, the prototype was designed as a diagnostic tool to detect changes in the fluids, tissues and blood vessels of the eye and brain.

“We have made calibration measurements on glucose samples in a cuvette [clear tube] to show that the concept works,” says Ansari. “At present, we are trying to make measurements in a model eye with a contact lens in front.”

In the next six months to a year, Ansari will try to measure glucose in animal and human eyes.

Easier Testing Technology Means More Testing

Experts agree that a reliable user-friendly glucose monitor that doesn’t require recalibrations will inspire people to monitor their glucose four to seven times a day and will also have a tremendous impact on the current $4 billion blood glucose self-monitoring market.

“Eighty percent of diabetics don’t monitor themselves even once a day,” says Garg. “A reliable monitoring device that merely alerts people to glucose extremes would in and of itself be great!”