Not too long ago, the idea of walking around with biometric wrist sensors, feeding health data to server farms thousands of miles away, would have been met with skepticism. Now the devices are ubiquitous. What makes wearable trackers ripe for a healthcare expansion? Their almost incomprehensible database of heartbeats, sleeping hours and steps counted. And the potential of that data in the realm of healthcare is just now coming to light. This in-depth Forbes article explores how FitBit, a leader in the fitness tracker market, is working to filter noise and find the signal in medical data-just as it did with fitness.