Back in February, a Garmin patent for wrist-based HbA1c tracking looked like an interesting one-off. It doesn't anymore.
Three separate filings are now converging on the same idea: estimating blood sugar markers from your wrist using light, no finger pricks, no sensors stuck in your arm. And the timing lands right as the Fenix 9 rumor mill hits peak heat.
Let's separate what the patents actually say from what people want them to say.
What the HbA1c Patent Describes
First, a quick reality check on what HbA1c even is. Glycated hemoglobin measures the percentage of your red blood cells carrying glucose, and it reflects your average blood sugar over roughly three months. It's the long-term view, not a live reading.
That distinction matters. Garmin's patent does not describe a continuous glucose monitor replacement. There's no live glucose number here, the way a Dexcom or Abbott CGM gives you one. Instead, the watch would shine several different wavelengths of light into the wrist, read the PPG (photoplethysmography) signals, and use those to estimate glycated hemoglobin. Think of it as a quarterly report on your metabolic health rather than a live ticker.
That's still a huge deal if it works. HbA1c is the number doctors use to diagnose and manage diabetes, and no consumer smartwatch can measure it today.
The other notable development: Garmin's HbA1c patent application is still pending, and it received a non-final USPTO Office Action in March, meaning formal examination is underway. An Office Action isn't an endorsement, it can include objections or rejected claims, but it does mean the application is moving through the system rather than sitting in a queue.
The Patent That Solves the Hard Part
Here's where it gets more interesting than a single speculative filing.
A separate Garmin patent called "Pressure compensation for wrist-based pulse spectrometry" explicitly discusses HbA1c measurement, and it tackles one of the practical problems that could make wrist-based readings garbage: how tight the watch sits on your arm.
Compressing blood vessels and tissue changes the optical signals used to calculate physiological measurements. If your watch is snug, your readings drift. Garmin's filing describes compensating for that wrist pressure across multiple optical wavelengths between roughly 600 and 1,000 nanometers, and calculating glycated hemoglobin from three PPG signals at different wavelengths.
The clincher: two of its inventors, Paul MacDonald and Christopher Kulach, also appear on Garmin's dedicated HbA1c patent. Same team, adjacent problems, overlapping timeline.
There's a third piece too. Garmin's wrist-worn optical cardiac monitor patent describes sensor arrangements using three optical transmitters with different wavelengths, including configurations across several red and infrared bands. The HbA1c patent, for its part, requires three separate wavelengths traveling along substantially the same optical path.
None of this proves the filings describe parts of one future Garmin sensor. But the overlap is hard to wave away. Garmin appears to be working not just on how to calculate HbA1c, but on the engineering problems that would make those calculations unreliable on an actual wrist.
Why Fenix 9 Is Part of the Conversation
The dates line up. 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. These projects have been underway long enough to influence a 2026 hardware generation.
And Garmin is clearly preparing new high-end hardware:
- A teardown of Garmin Connect 5.27 uncovered six coordinated outdoor-watch records that could belong to a future Fenix 9 family, though Garmin hasn't confirmed their identity.
- Garmin model A05170, an unannounced premium wrist-worn device, recently appeared at the FCC with LTE and satellite connectivity. Fenix 9, or a Pro version of it, is one possible identity. The filing keeps its photos confidential, so it tells us nothing about the optical sensor on the back.
If the Fenix 9 arrives with a substantially redesigned optical module, especially one with additional red and infrared emitters, the connection to Garmin's spectroscopy work gets a lot more interesting.
The Reality Check
Now the part that should cool off the hype.
There's still a big gap between Garmin researching wrist-based HbA1c estimation and shipping the feature in a watch. So far there's no public evidence of clinical validation, regulatory work, or anything tying the technology directly to Fenix 9. Independent coverage, including a TechRepublic analysis, makes the same point: the patent trail is real, the product connection is not.
Two more caveats worth spelling out:
- Even if Fenix 9 introduces a new optical sensor, that alone proves nothing. Garmin could redesign the sensor for heart-rate accuracy, Pulse Ox, ECG, power efficiency, or something else entirely. What would matter is evidence of a multi-wavelength optical setup matching the patents.
- Regulators have not blessed this category. The FDA has not authorized any wrist-worn feature that measures blood glucose without piercing the skin, and it has actively warned consumers about smartwatches making exactly those claims. Whoever cracks this first, Garmin, Apple, or Samsung, faces a regulatory climb before it becomes a product feature rather than a wellness curiosity.
Garmin's broader interest in metabolic health is real and growing. In May, Garmin Health published a Diabetes Insight Report looking at wearable data alongside CGMs and third-party diabetes programs. But that's Garmin analyzing data from other companies' sensors, not measuring glucose itself.
Bottom Line
The honest summary: Garmin is researching wrist-based HbA1c seriously enough to have three related patents in flight, shared inventors, and work on the practical reliability problems that sink most optical health claims. The priority dates go back to 2022 and 2023, which puts the research squarely in the window for next-generation hardware.
What Garmin is not doing is promising you a blood sugar reading on the Fenix 9. No clinical validation, no regulatory filings, no confirmed sensor.
Watch the Fenix 9's sensor hardware when it surfaces. If it's a multi-wavelength red and infrared setup, this story graduates from patent-watch to product-watch. Until then, it's the most credible wrist-glucose program in the category, and still years away from your wrist.
For the broader Fenix 9 picture, see our Fenix 9 rumors roundup and the three-model launch report.