Popular among bikers, rappers, and rebellious teenagers, the tattoo may become the identifying mark of a perhaps unlikely group—diabetics.

Scientists at the Cambridge-based Draper laboratories are developing nanoparticle tattoo ink that changes color to indicate glucose levels in the skin. The researchers are aiming to test the ink on mice by the end of the month, said Heather Clark, a member of Draper’s biomedical engineering group.

The small tattoos could replace the often painful finger-pricks that diabetics endure up to twelve times a day to monitor their blood glucose levels. The ink is composed of a glucose-detecting molecule, a color changing dye, and a molecule that mimics glucose, all of which float in spherical polymer bead.

When a glucose-detecting molecule approaches the edge of the bead, it should latch onto either a glucose molecule or the glucose-like molecule.

If glucose levels are high, the detecting molecule should attach to glucose in the bead, making the ink appear yellow. If glucose levels are low, the molecule should latch onto the glucose mimic, causing the ink to turn purple. A healthy level of glucose would be represented by a color somewhere in between, explained Clark.

Clark and her colleagues’ original goal was not to produce a glucose-measuring ink, but rather one to measure sodium levels in the skin, she said. When that project showed promising results in mouse trials, the director of the bioengineering department at the time challenged the researchers to apply a similar approach to glucose. Though they were initially skeptical of the project’s feasibility, Clark and her team now hope to begin animal testing in a few weeks.

According to Clark, one concern that has been voiced about the technology is whether glucose measurements taken from the skin are as accurate as those taken from the blood. Others have asked whether this technology—which is still years away from being tested in humans—could be read through different skin pigments.

But Gordon C. Weir, a professor of medicine at the Medical School’s Joslin Diabetes Center, remained cautiously optimistic.

“Everyone is always coming up with new ideas but if this technology does what it says it does, I believe it would be a great tool for diabetes patients,” he said.