Smartwatches as Medical Devices: Health-Tech Revolution and Its Limits

Author: Marie-Astrid Langer
Publication Date: 01.01.2026
Source: NZZ Technology

Summary

Smartwatches are increasingly developing into personal health advisors and can today warn of high blood pressure or detect atrial fibrillation. Leading manufacturers such as Apple and Garmin are investing heavily in improving biometric sensors and researching breakthroughs such as non-invasive glucose measurement. While technological advances are impressive, questions remain about the reliability and medical applicability of this data.

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Detailed Summary

The Evolution of Wearable Technology

The history of smartwatches began 23 years ago with an unconventional idea: Scott Burgett and his colleagues at Garmin taped GPS devices to their wrists with duct tape to record their jogging routes. This small innovation marked the beginning of an industry that flourishes today. The global market for wearables and health-tech devices reached a volume of 62 billion dollars in 2024.

Strategic Expansion of Tech Corporations

Apple has recognized and expanded health as a business field. CEO Tim Cook made a remarkable statement: Apple's greatest societal contribution might retrospectively lie in the health sector – a surprising statement for a corporation primarily known for consumer electronics. Garmin founded its own health division in 2014. Both companies are today market leaders in the smartwatch segment.

Apple is developing an AI-powered virtual doctor under the project name "Mulberry," which consolidates data from smartphones, smartwatches and other devices and provides personalized health recommendations. The goal is for patients in the future to simply open the "Health" app during doctor visits and present the doctor with a detailed overview of their health status.

Technology of Biometric Sensors

Modern smartwatches are equipped with complex sensors: GPS, barometric altimeters, gyroscopes, thermometers and especially light sensors. These light sensors function according to an elegant principle: they send green, red or infrared light through the skin, blood and tissue. The molecules absorb the light differently depending on the oxygen content of the hemoglobin. The reflected light wavelengths allow conclusions about:

• Oxygen saturation
• Heart and respiratory rate
• Sleep phases and duration
• Stress levels
• Menstrual cycle
• Atrial fibrillation

Giuseppe Olivadoti from Analog Devices – the manufacturer of sensors in leading smartwatches – emphasizes that data accuracy is heavily dependent on consistent wearing position. It is a "trade-off between data correctness and comfort." Olivadoti is confident that sensor technology will continue to advance and new health indicators will become possible through the combination of multiple sensor data.

The Holy Grail: Non-Invasive Glucose Measurement

The non-invasive determination of blood sugar levels without a needle prick is considered the holy grail of the health-tech industry. Worldwide, there are hundreds of millions of diabetics who check their insulin levels multiple times a day by pricking their fingers. A smartwatch-based solution would be life-changing for these patients and a huge business model for manufacturers.

Apple is investing hundreds of millions of dollars in a 15-year major project to develop a non-invasive glucose monitor based on light absorption. Competition comes from pharmaceutical corporations such as Abbott Laboratories. Scott Burgett calls this the "Manhattan Project of our time," but warns against false hopes: the glucose-related blood level fluctuations are minimal. The algorithms must not only detect these minimal deviations, but also reliably rule out that other factors trigger the fluctuations. Reliability is critical because users would inject insulin based on the measured values – measurement errors could have serious health consequences.

Other Innovative Projects

Garmin is currently testing a function to determine alcohol levels to help drivers recognize whether their blood alcohol level exceeds a threshold. Here too, measurement errors could be potentially fatal.

External companies such as Orbit Health are already using sensors from higher-priced Garmin watches to measure the extent of tremor in Parkinson's patients. Acceleration sensors and gyroscopes capture hand movements multiple times per second and specialized algorithms evaluate this data.

Scientific Validation

Garmin has launched a large-scale study with King's College London. Study leader Josip Car praises the quality and accuracy of Garmin sensors. The study with 40,000 participants examines how exercise affects the health of pregnant women. This shows that researchers are increasingly convinced of the reliability of smartwatch data.

Key Takeaways

• Technological Progress: Smartwatches have evolved from simple fitness trackers to sophisticated health measurement devices that integrate complex biometric sensors.

• Market Potential: With 62 billion dollars in revenue in 2024, the wearables market has grown massively and is considered the next wave of disruption in the tech industry.

• Strategic Investments: Apple and Garmin as market leaders are investing billions in AI systems and sensor technology for preventive and therapeutic applications.

• Glucose Measurement as Key Project: Non-invasive blood sugar measurement is being researched by several corporations with enormous effort, but presents technical and safety-critical challenges.

• Scientific Validation: Universities and research institutes are increasingly collaborating with wearable manufacturers and confirming the quality of sensor data.

• Critical Questions About Reliability: Despite progress, safety concerns remain – especially for applications that lead to medical decisions (e.g., insulin injections).

• Position Dependency: The accuracy of measurements depends heavily on how and where users wear their devices – consistency is critical.

• Interplay of Multiple Sensors: In the future, new health indicators will be possible through the combination of data from multiple sensors.

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