Smartwatches, rings and activity trackers can estimate movement, heart rate, sleep and other health-related measurements. Some functions are regulated medical-device features; others are wellness tools. A reading may be useful, inaccurate or clinically unimportant depending on the device and situation.
What wearables may measure
- steps, activity and estimated energy use
- heart rate and selected rhythm patterns
- sleep duration and movement
- oxygen saturation, temperature or respiratory rate
An estimate is not a diagnosis
Accuracy can be affected by movement, skin contact, device position, tattoos, circulation, temperature and algorithms. Consumer sleep stages and “stress scores” are estimates, not clinical assessments. An irregular-rhythm alert needs confirmation, and a normal result cannot rule out disease when symptoms are present.
Blood glucose and blood pressure claims
The FDA has not authorised a smartwatch or ring that independently measures glucose without piercing the skin. Unauthorised blood-pressure features may also be inaccurate. Never adjust diabetes or blood-pressure medicine using an unverified reading.
When to seek help
Seek urgent assessment for chest pain, fainting, severe breathlessness, new weakness or difficulty speaking regardless of the display. Save repeated alerts and discuss them with a healthcare professional rather than repeatedly checking.
Privacy and implanted devices
Wearables may collect location, sleep, heart and reproductive-health data. Review permissions, security, retention and data sharing. Magnets in some watches can interfere with certain pacemakers or defibrillators; follow device and clinical guidance.
Using a wearable sensibly
- Check intended purpose and regulatory status.
- Follow fitting instructions.
- Look at trends, not one isolated number.
- Do not let tracking replace professional care.
- Pause notifications if monitoring increases anxiety.
This article provides general educational information and does not replace medical assessment.
Sources
- US FDA: Sensor-Based Digital Health Technology
- US FDA: Blood Glucose Claims
- US FDA: Unauthorised Blood-Pressure Devices
Last reviewed: 28 August 2026