A wearable medical device is a device worn on or attached to the body that measures physiological signals continuously or repeatedly during ordinary daily life. The category spans clinical grade equipment such as ambulatory ECG patches, continuous glucose monitors, insulin pumps and ambulatory blood pressure monitors, as well as consumer products that have acquired regulated functions.
Their clinical appeal is that they capture what happens between appointments. An intermittent arrhythmia, nocturnal hypoglycaemia or a gradual decline in activity is invisible in a ten minute consultation but obvious in continuous data.
The dividing line is intended purpose, not sophistication. A smartwatch that reports step count and resting heart rate for general fitness is a wellness product. The same watch, when it runs a function intended to detect atrial fibrillation, is performing a medical purpose and that function requires regulatory clearance. Manufacturers often ship a general wellness wearable with specific regulated features layered on top, which is why marketing claims are scrutinised so closely.
Beyond clinical validation, wearables carry the full weight of device engineering: biocompatibility of anything in skin contact, battery and electrical safety, wireless coexistence, cybersecurity of the device and its companion app, and a defined plan for software updates and end of support. Data protection deserves particular attention, since continuous physiological data is highly identifying and the boundary between clinical use and commercial analytics needs to be explicit to the person wearing it.
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