People with type 1 diabetes must prick their fingers several times a day to test their blood sugar levels. Though the pain is minor, the chore interferes with daily life. Two MIT labs are now working on new blood glucose sensors that would be less invasive and potentially more accurate.

"Diabetes is an enormous problem, global in scope, and despite decades of engineering advances, our ability to accurately measure glucose in the human body still remains quite primitive," says Michael Strano, an associate professor of chemical engineering. "It is a life-and-death issue for a growing number of people."

Strano and one of his postdocs, Paul ­Barone, are devising a system based on a "tattoo" of glucose-detecting nanoparticles injected below the skin. The "ink" is made of carbon nanotubes wrapped in a polymer that fluoresces when it encounters glucose.

To get glucose readings, the patient would wear a monitor, similar to a wristwatch, that shines near-infrared light on the tattoo to detect and measure the resulting fluorescence. The nanoparticles would gradually break down, so the patient would need to receive a new injection every six months or so. Safety tests would need to be done before the nanotubes could be approved for use in humans, says Strano.

Scientists in MIT's Spectroscopy Laboratory are working on a different type of glucose sensor that does not require nanoparticle injections. The sensor, originally envisioned by the lab's late director, Professor Michael Feld, is based on Raman spectroscopy, which can detect a substance's chemical composition by shining near-infrared light on it.

Spectroscopy Lab graduate students Ishan Barman, SM '07, and Chae-Ryon Kong hope to begin testing their sensor in healthy volunteers this fall. Most tabletop Raman spectroscopy devices require a large lab bench, but they are working on a smaller model that could be used in a doctor's office or a patient's home.

Both groups ultimately hope to connect a wearable glucose sensor to an insulin pump, effectively creating an artificial pancreas that would detect dangerously high glucose levels and react accordingly.

"The most problematic consequences of diabetes result from relatively short excursions of a person's blood sugar outside of the normal metabolic range--following meals, for example," says Strano. "If we can detect and prevent these excursions, we can go a long way toward reducing the devastating impact of this disease."