Wearability May Be a Source of Instability

Wearables worn near the wrist, with energy-based sensors, e.g., optical, should not be assumed to be continuous.

The implementation of Apple's blood oxygen function is instructive:

"The Blood Oxygen app periodically measures your blood oxygen level throughout the day if background measurements are turned on, but you can also take an on-demand measurement at any time.

1. Go to the Blood Oxygen app on your Apple?Watch.
2. Rest your arm on a table or in your lap, and make sure your wrist is flat, with the Apple?Watch display facing up.
3. Tap Start, then hold your arm very still during the 15-second countdown.
4. At the end of the measurement, you receive the results. Tap Done.

Note: To get the best results, the back of your Apple?Watch needs skin contact. Wearing your Apple?Watch not too tight or too loose, with room for your skin to breathe, and flush with the top of your wrist, helps ensure successful Blood Oxygen measurements. For more information, see the Apple Support article How to use the Blood Oxygen app on Apple?Watch." - Apple

Movement of the Wrist Wearable Modulates the Signal

The optical path must be stable to achieve an accurate measurement. For this reason, wearables are opportunistic when conditions are ideal, such as sleeping—or on demand- when the wearer requests a measurement and while complying with the limitation.

Optical gadgets worn at the wrist or on the forearm do not present stable optical paths unless the wearer is motionless. Variations in the optical path while moving are unlikely to be accounted for by a 3D accelerometer—the path must be stable when the spectra are measured.

Errors in the optical measurement may limit the veracity of the detailed analyses.

Future wearables promise glucose measurement as an alternative to $3/day over-the-counter, factory-calibrated CGMS (continuous glucose monitors)from two U.S. sponsors—the over-the-counter CGMs stream glucose data at one-minute or five-minute intervals.

Explicitly stating the Indications For Use of a noninvasive glucose method is an excellent starting point to understand the direction of the noninvasive glucose research programs.

When might an optical noninvasive glucose wrist-wearable process potentially useful glucose information despite being less accurate than an FDA-cleared CGM?

• While the wearer is asleep; or
• On demand, while the wearer rests their arm on a table or their lap; and
• The forearm is not moving

While wearable noninvasive glucose concepts face challenges, interesting applications abound.

#glucose #noninvasive #diabeticinvestor #Abbott #Dexcom #wearables #simianalytica