Eight-year-old Julia Balobeck needs to prick her fingers so many times each day that the tips of her digits have started to turn numb and black. Even at her age, she understands that the needle sticks are crucial to keep track of her blood sugar levels and manage her Type 1 diabetes, but she’d really like someone to find a better way.

Help may be on its way for Balobeck and other diabetics who must jab themselves as many as 10 times each day to get that critical drop of blood that will reveal glucose levels and indicate whether a shot of insulin is needed.

Scientists are starting to test a kind of sensor that changes color with rising blood sugar levels. The high-tech tattoo, which is about the size of the clicker on the end of a ballpoint pen, is made up of tiny spheres that are injected into the outermost layer of skin. These nanospheres contain a special kind of ink that reacts with glucose, explains the tattoo’s inventor, Heather Clark, a biomedical engineer at Draper Laboratory in Cambridge, Mass.