Google’s latest smartwatch is pushing wearable technology further into territory once reserved for the doctor’s surgery, promising to detect changes associated with blood pressure, insulin resistance and breathing without needles, cuffs or laboratory tests.
Unveiled on August 12, the Pixel Watch 5 introduces a suite of new “Health Guardian” features designed to monitor subtle physiological changes over time rather than simply count steps or record workouts.
The most striking additions are monthly summaries covering blood pressure trends, insulin resistance trends and sleep breathing quality.
Google says the underlying models were trained using billions of minutes of sensor data from users who opted into research and validated against clinical reference measurements.
That raises an increasingly important question for the wearables industry: at what point does a smartwatch stop being a fitness gadget and start resembling a medical monitoring device?
Looking for patterns rather than taking measurements
The distinction is important.
The Pixel Watch 5 does not replace a blood-pressure cuff and it does not directly measure blood glucose or provide a clinical diagnosis of insulin resistance.
Instead, Google is using data collected continuously from sensors on the wrist and analysing changes over longer periods.
Its new Insulin Resistance Trends feature examines several weeks of physiological information to identify shifts associated with metabolic health without requiring a blood sample.
Google says the feature is intended to identify trends rather than provide real-time glucose measurements or screen users for diabetes.
Blood Pressure Trends works along similar lines.
Rather than displaying a conventional systolic-over-diastolic reading such as 120/80 mmHg, the technology looks for persistent changes that could indicate that a user’s cardiovascular pattern has shifted.
Google explicitly cautions that the feature is for general wellness and information purposes and should not be used to manage blood pressure, alter medication or replace conventional monitoring.
The technology therefore sits in an unusual middle ground: it is not performing the same test as a medical instrument, but it is attempting to identify changes that could prompt someone to seek further investigation.
A laboratory on the wrist
Modern smartwatches are able to do this because they contain a growing collection of miniature sensors.
Photoplethysmography, or PPG, uses light to detect changes in blood volume beneath the skin and is already widely used to calculate heart rate.
Accelerometers measure movement, while other sensors can monitor signals including blood oxygen patterns, skin temperature and electrical activity associated with the heart.
The real technological shift, however, may be happening in the software.
Rather than relying on a single sensor reading, machine-learning models can combine large quantities of data gathered over days or weeks and search for changes that would be difficult for a wearer to notice.
That is effectively turning the smartwatch from a device that records individual measurements into one that looks for patterns in human physiology.
Detecting breathing emergencies
Pixel Watch 5 also introduces Breathing Emergency Detection.
Google says the system combines information from multiple sensors, including PPG, the accelerometer and barometer, with on-device AI to watch for severe and sustained declines in oxygen saturation.
If an apparent respiratory emergency is detected while the wearer is unconscious, the watch may be able to contact emergency services and transmit the user’s location.
The feature is initially being introduced in selected European markets and Google stresses that it cannot identify every emergency and is not a substitute for prescribed oxygen-monitoring equipment.
Health technology becomes continuous
Healthcare has traditionally depended heavily on snapshots.
A patient visits a clinic, has their blood pressure measured or provides a blood sample and receives a result representing that particular moment.
Wearables introduce a different model.
A watch can potentially collect information for 20 or more hours every day, building a longitudinal picture of changes that occur between visits to a doctor.
Google said in June that more than half of Wear OS users wear their devices every day, while its most active users keep them on for more than 23 hours a day.
That continuous stream of data could ultimately prove as significant as improvements in the individual sensors themselves.
The Pixel Watch 5, which starts at US$399 and goes on sale from August 20, is therefore interesting for more than its specifications.