This document discusses various wearable technologies that can benefit athletes and people with diabetes. It describes smartwatches that track running performance and heart rate, headphones that monitor heart rate during exercise, and a watch that can measure blood sugar and lactic acid levels without finger pricks. Google is developing smart lenses that can detect early signs of diabetes and glaucoma by monitoring glucose levels through tear fluid. Wearables provide health and fitness tracking in convenient, hands-free ways.