Measuring Blood Sugar: The Eyes Have It

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June 24, 2001 (Philadelphia) -- Day in, day out, millions of diabetics prick their finger and squeeze a tiny drop of blood on a strip of paper to measure their blood sugar levels. It's part of the hassle of managing this chronic disease -- a real pain that soon may be a thing of the past if the latest research pans out.

In the not-too-distant future, bloodless, painless ways will be available for measuring and potentially even treating high levels of sugar, or glucose, in the blood, according to new research presented here Friday at the annual meeting of the American Diabetes Association (ADA). That will allow people with diabetes to monitor their sugars more often, leading to improved control and lower risk of diabetes complications, including nerve, eye, and kidney damage.

The first bloodless monitoring device for people with diabetes may be available as early as 2004, says David C. Klonoff, PhD, medical director the Dorothy L. and James E. Frank Diabetes Research Institute at Mills Health Center in San Mateo, Calif. It will work by casting an invisible light on either the skin or eye and measuring the interaction of the light with glucose. From there a computerized meter calculates glucose levels.


Also being previewed at the ADA meeting are contact lenses that measure glucose levels in tears. A person wearing the lenses presses a button on a small device that shines a light on the lens, and -- voila! -- a glow-in-the-dark phenomenon called fluorescence occurs, says Wayne F. March, MD, professor and chairman of ophthalmology at the University of Texas Medical Branch in Galveston, Texas.

"Tears contain glucose that's proportional to [the amount of] blood glucose," he tells WebMD, "and the contact lens can sense the glucose concentration on tears. The patient gets a reading and if the tear glucose is high, so is the blood sugar."

March and colleagues tested the new lenses on nine people with type 2 diabetes and three people without diabetes and found the contact not only corrected vision, but also accurately measured glucose. In the future, the same technology may be applied to eyeglass lenses, he says.


Ultimately, says Klonoff, "Where all this technology is eventually heading is toward an artificial pancreas."


The pancreas, the organ that produces the hormone insulin to metabolize glucose is not functional in people with diabetics. Creating a replacement organ is the Holy Grail of diabetes research. At the ADA meeting, French doctors reported early success in their bid to accomplish this.

"It's based upon an insulin pump that is surgically implanted under the skin in the abdomen wall, providing a two- to three-month supply of the hormone insulin," explains lead researcher Eric Renard, MD, of the Hopital Lapeyronie in Montpellier, France. "And a glucose sensor is implanted by the jugular vein."

The pump looks like a yo-yo; the insulin sensor is about 10 inches long and about 1/10 inch in diameter. The surgery itself requires general anesthesia and takes about 45 minutes to perform.

When glucose levels are out of whack, a signal is sent to the insulin pump via a wire implanted under the skin -- essentially aping the function of a healthy pancreas.

So far, so good, says Renard, who implanted the device in two men at the end of last year. They have been followed for seven months and are doing well, he says. Since, then he has implanted the system in five more people.


"Treating diabetes without injections and without fingersticks sounded, until now, like a dream," says Renard. "But this dream may become a reality"

Unfortunately, no technique lives up to this promise today. In March, the FDA approved the GlucoWatch, a watch-like device that helps people with diabetes measure their glucose via tiny electric currents. It is "the first step toward noninvasive, continuous glucose monitoring, but it's only a first step," says Robert F. Monoson, MD, chief medical officer of DMCare Inc.

The problem with the GlucoWatch, he says, is that it does not allow for changes of insulin dosing based on numbers.

We need a "glucose monitor that's easy to use, continuous, and where the information is transmitted someplace," says Monoson, who has diabetes. To that end, he is helping develop a wireless glucose meter that tells people what their blood sugar is and what they should do about it.


"Data would be sent wirelessly to a remote site, analyzed, and sent right back on the spot so they can eat differently or change their insulin dose," he says. Also in the works at DMCare is a Palm Pilot-like device that allows a person to enter what they want to eat, and the computer then tells them how much insulin they will need if they do. He expects both products to be available next year.

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