Garmin’s glucose tracking plans look more serious ahead of Fenix 9

Garmin’s wrist-based HbA1c patent was interesting when it popped up in February, but it is starting to look like there is more to it than one random filing. A few related patents show the company is working on the optical hardware and even on how tightly the watch sits on your wrist, which could affect HbA1c readings.

When we first covered Garmin’s HbA1c patent, the idea was pretty easy to understand. The watch would shine several different wavelengths of light into the wrist, read the PPG signals and use that to estimate glycated haemoglobin. So this would not be live glucose tracking like a CGM, but more of a longer-term view of where your glucose levels have been.

This goes beyond one glucose patent

There has been some movement since February. Garmin’s HbA1c patent application remains pending and received a non-final USPTO Office Action in March, meaning the examination process is now underway.

That is not an endorsement of the technology, and an Office Action can include objections or rejected claims. What is more interesting is what shows up when Garmin’s other optical-sensing patents are viewed alongside it.

A separate Garmin filing called Pressure compensation for wrist-based pulse spectrometry explicitly discusses HbA1c measurement. It describes compensating for the pressure a watch applies to the wrist, because compressing blood vessels and tissue can alter the optical signals used to calculate physiological measurements.

The filing goes into considerable detail, including pressure compensation across multiple optical wavelengths between roughly 600 and 1,000nm. It also describes calculating glycated haemoglobin from three PPG signals at different wavelengths, and two of its inventors, Paul MacDonald and Christopher Kulach, also appear on Garmin’s dedicated HbA1c patent.

That is a more interesting clue than another generic mention of glucose in a patent. Garmin appears to have been working not only on how to calculate HbA1c, but on one of the practical problems that could make those calculations unreliable on an actual wrist.

There is another piece of the puzzle. Garmin’s wrist-worn optical cardiac monitor patent describes sensor arrangements using three optical transmitters with different wavelengths, as well as configurations operating across several red and infrared wavelength bands.

The HbA1c patent also requires three separate wavelengths travelling along substantially the same optical path. That does not prove these filings describe parts of one future Garmin sensor, but the overlap is difficult to ignore.

And then there is Fenix 9

The timing makes Fenix 9 particularly interesting. Garmin’s HbA1c work claims priority back to June 2023, the pressure-compensation filing dates to October 2023, and the optical-monitor work goes back to 2022, so these projects have been underway long enough to influence a 2026 hardware generation.

We already know Garmin is preparing new high-end watches. Our Garmin Connect 5.27 teardown uncovered six coordinated outdoor-watch records that could belong to a future Fenix 9 family, although Garmin has not confirmed their identity.

There is also Garmin model A05170, an unannounced premium wrist-worn device that recently appeared at the FCC with LTE and satellite connectivity. Fenix 9 or Pro version of the same is one possible identity for that watch. But the filing keeps its external and internal photographs confidential, so it tells us nothing about the optical sensor on the back.

And that sensor is now the bit worth watching. If Fenix 9 arrives with a substantially redesigned optical module, particularly one with additional red and infrared emitters, the connection with Garmin’s spectroscopy work becomes much more interesting.

Why Fenix 9 is still a long shot

There is still a big gap between Garmin researching wrist-based HbA1c estimation and putting the feature into a shipping watch. So far, we have found no public evidence of clinical validation, regulatory work or anything else that ties the technology directly to Fenix 9.

Garmin’s wider interest in metabolic health is clearly growing. In May, Garmin Health published a Diabetes Insight Report looking at Garmin wearable data alongside CGMs, AI platforms and third-party diabetes programmes, but that is separate from Garmin measuring glucose or HbA1c itself.

Even if Fenix 9 introduces a new optical sensor, that alone would tell us very little. Garmin could redesign the sensor for better heart-rate accuracy, Pulse Ox, ECG performance, power efficiency or entirely different health metrics.

What would make the HbA1c connection more interesting is evidence that a new sensor uses the sort of multi-wavelength optical setup described in Garmin’s patents. Until we see something like that, linking Fenix 9 directly to glucose tracking would be mostly guesswork.