DALLAS, Texas — For the last five years, Seoyun “Matthew” Lee has pricked his fingertips at least once a day to test a drop of blood. If the amount of glucose, a simple sugar, is too high, he must get a shot of insulin to lower it. These daily finger pricks are “really lifestyle-hampering and invasive,” Matthew says. So he developed an alternative — a wearable patch. It turns yellow when glucose levels are too high.