Nature Medicine : Sounding out sugar

Nature Medicine : Sounding out sugar

Nature Medicine : Sounding out sugar

SARA ABDULLA

As little as three years from now, diabetics may jettison their needles, a report in the latest Nature Medicine (March 2000) suggests. Why? Because, thanks to ultrasound, they could instead be testing their glucose levels painlessly through their skin. The very same technology might even sneak drugs into the blood.

Ultrasound is best known for giving us a blurry, but tantalizing window on the growing foetus during pregnancy. But Joseph Kost of Ben-Gurion University, Beer Sheva, Israel and colleagues have found that ultrasound of far lower frequency (20 kHz) than that used to scan babies the world over, widens the gaps between the fatty layers of human skin, making it more permeable. This allows molecules such as glucose to seep out of tiny surface blood vessels and through the skin, without it ever being punctured or even damaged in any way.

After assessing their technique on cadaver skin and in rats, the researchers tried it out on humans. Seven volunteers with type 1 diabetes, to be precise. A two minute blast of ultrasound, they found, was enough to increase skin permeability for up to 15 hours. Indeed in a clinical trial now underway, half a minute is proving enough.

Patients had a small glass tube, filled with soapy solution, fixed to the skin on their arm. Kost's team put an ultrasound probe into this tube, and, after blitzing the set up with sound waves too high to be audible to the human ear, they filled the tube with saline solution. Then they applied a
vacuum to the tube to suck fluid from the spaces between the patients' skin cells and into the saline.

The amounts of glucose thus extracted correlate closely with known blood glucose measures -- an important consideration if this method is to be used in the clinic.

Ultimately the researchers envision that this technology could form part of a 'closed loop system', that could monitor a given variable -- such as glucose -- and also deliver appropriate therapy -- in this case, insulin. "Further research on the portability, stability and long-term safety," say the team, should hopefully lead to, hand-held, battery-operated devices or even wristwatch-sized glucose sensors.

© Macmillan Magazines Ltd 2000 - NATURE NEWS SERVICE

Visit our new "Ask The Doctor" section today!