Checking blood glucose levels used to mean a finger prick and a test-strip, but researchers at the University of Tokyo are offering a different approach: a glowing skin implant. After being injected with the 1 mm wide filament, it monitors your blood sugar by glowing when your level changes. Based on existing glowing glucose sensor technology, this hydrogel fiber is considered more accurate and stable than its predecessors, plus it requires no oxygen to function. So far, it’s worked in mice for up to 140 days. Note to future human patients: don’t eat a candy bar before you go to bed unless you want your arm looking like a nightlight.