When postdoctoral fellows at Harvard and researchers at MIT start talking about tattoos, chances are they are not discussing dolphins or barbed wire. These scientists are behind the “Dermal Abyss” project and their mission is to develop color-changing tattoo ink capable of alerting the owner of certain medical conditions.

Technically speaking, this ink is a combination of colorimetric and fluorescent biosensors that can report on the concentration of sodium, glucose, and pH in the interstitial fluid of the skin. In layman’s terms, the ink can turn from green to brown as your body’s glucose rises, allowing you time to control your blood sugar before it becomes a serious problem.

It is predicted that 48.3 million people in the US will have diabetes by 2050 and the number of people with diabetes worldwide is expected to increase to 366 million by 2030. Thankfully, the days of constantly pricking your finger for a drop of blood may be over for those willing to undergo a few hours’ pain for a medical tattoo.

For those of us who like to keep our medical information private, the researchers are working on ink that is only visible under certain wavelengths of light. They predict that people who require constant monitoring such as astronauts might be their first target audience, but it’s easy to imagine athletes sporting these to monitor hydration throughout a game.