They trained an ML model that predicts blood glucose based on age, sex, GPS location, and Apple Pay transactions. Just bought a #3 combo at Taco Bell and arrived at home? Blood glucose spikes 15 minutes later.

"We see that your blood glucose is low. You are currently 0.3 miles from a Starbucks(TM)."

You can check out the claims that Rockley Photonics (Apple sensor supplier for the watch) made in their SPAC presentation or their patents

https://rockleyphotonics.com/wp-content/uploads/2021/03/Rock...

https://patents.justia.com/assignee/rockley-photonics-limite...

From the linked article: Apple has been revealed to be the largest customer of the British electronics start-up Rockley Photonics, The Telegraph reports.

Rockley Photonics has developed non-invasive optical sensors for detecting multiple blood-related health metrics, including blood pressure, blood glucose, and blood alcohol levels, many of which are only normally detectable with more invasive dedicated medical equipment. Rockley's sensors beam infrared light through a user's skin, much like the existing sensors on the back of the Apple Watch for detecting heart rate and blood oxygen levels.

Edit: formatting

This is straight-up tricorder level shit if it pans out. Definitely upgrading from my v4 if that's the case.

This still doesn't explain how it works. Oxygen and heart rate can be done with light, this is well known, but how does it measure glucose and alcohol levels and blood pressure?

If someone is really drunk you can smell the alcohol standing near them. Not sure about glucose but possibly it's detecting chemicals diffusing through the skin or pores?

It would be very interesting how this would reliably work across a diverse population without some sort of calibration step. I am skeptical, but it is Apple.

If they can get blood glucose working through the watch, they are going to sell tens of millions of additional units.

Blood oxygen levels are also measured optically already. If you can find an optical property of blood (that depends on a particular substance) which can be measured through the skin (infrared light can penetrate skin and flesh to some degree), you can build a sensor for it.

Sure but oxygenation is strongly correlated with hemoglobin color, so it's very easy.

Blood pressure, on the other hand, is very difficult to measure, and it fluctuates wildly based on a wide variety of confounding factors. It would be amazing if they figured out a way to get this information optically.

Infrared. Got it. Thanks.

Could be something else. The wikipedia page on this technology (https://en.wikipedia.org/wiki/Noninvasive_glucose_monitor) mentions “bioimpedance spectroscopy, microwave/RF sensing, fluorescence technology, mid-infrared spectroscopy, near infrared spectroscopy, optical coherence tomography, optical polarimetry, raman spectroscopy, reverse iontophoresis, and ultrasound technolog“

That page also claims there isn’t any clinically or commercially viable product yet. That seems out of date to me, given that https://www.labiotech.eu/best-biotech/needle-free-glucose-mo... mentions 8 devices you can buy now.

> That page also claims there isn’t any clinically or commercially viable product yet. That seems out of date to me, given that https://www.labiotech.eu/best-biotech/needle-free-glucose-mo... mentions 8 devices you can buy now.

"needle free" !- "non-invasive".

Several of those devices are implanted subdermally.

> raman spectroscopy

And now I can’t stop thinking about wearing a Raman spectrometer on my wrist :)

It is called near-infrared spectroscopy ("NIRS") and you can read more about it here:

https://en.wikipedia.org/wiki/Near-infrared_spectroscopy

There has been a fair amount of research and (seeming) success in this area: https://www.medicaldesignandoutsourcing.com/mit-researchers-...

Not sure how close it is to being out of the lab but it definitely seems doable.

> Rockley’s optical technology enables the miniaturization of sensing devices necessary for the evolution of a wearable spectrometer [0]

If you have a wearable spectrometer (i.e. measure the wavelengths that are reflected), and a variable light source (i.e. control the frequencies sent into the body), you can isolate repeating patterns, even for molecules like glucose: https://youtu.be/xMa1BQ8z9C0?t=541

I'm still not sure how they can tell the parts per million, etc. Probably through multiple samples over time, or multiple veins.

[0] Page 18: https://rockleyphotonics.com/wp-content/uploads/2021/03/Rock...

Sweat analysis of some sort

Maybe Elizabeth Holmes is helping out?