Apple makes major progress on no-prick blood glucose tracking for its watch

There’s still years of work ahead, but the move could upend a multibillion-dollar industry. Roughly 1 in 10 Americans have diabetes, and they typically rely on a device that pokes the skin for a blood sample. There are also patches from Dexcom Inc. and Abbott Laboratories that are inserted into the skin but need to be replaced about every two weeks.

Apple is taking a different approach, using a chip technology known as silicon photonics and a measurement process called optical absorption spectroscopy.

The system uses lasers to emit specific wavelengths of light into an area below the skin where there is interstitial fluid — substances that leak out of capillaries — that can be absorbed by glucose. The light is then reflected back to the sensor in a way that indicates the concentration of glucose. An algorithm then determines a person’s blood glucose level.

Hundreds of engineers are working on the project as part of Apple’s Exploratory Design Group, or XDG, a previously unreported effort akin to X, the moonshot division of Alphabet Inc. It’s one of the most covert initiatives at the famously secretive Apple.

Even fewer people are involved in it than the company’s self-driving car undertaking, overseen by the Special Projects Group, or the mixed-reality headset, which is being developed by its Technology Development Group.

The news weighed on shares of diabetes technology companies on Wednesday, with both Dexcom and Abbott falling more than 3% before recovering. Apple gained 0.3% to $148.91 by the close in New York.