Garmin recently filed a patent that outlines how a smartwatch could estimate HbA1c using light signals. And it points to a different direction than the usual hype around continuous glucose monitoring.
The filing describes a system that uses a technique called pulse spectrometry to estimate glycated hemoglobin. This is better known as HbA1c, a marker that reflects your average blood glucose over the past two or three months. What stood out to me is that Garmin didn’t just mention glucose as a vague possibility. The patent includes equations, sensor layout and processing logic to show exactly how it might work.
Why long-term glucose tracking makes more sense for most people?
HbA1c is actually what doctors actually use to diagnose and monitor type 2 diabetes. It’s more useful if you’re trying to get a sense of how your body handles carbs over time. You can have perfect fasting glucose and still have a poor HbA1c score. And most people wouldn’t know it.
From a wearable tech point of view, this makes way more sense than chasing post-meal spikes. As someone who has written a review of a continuous glucose monitor, they are a bit overwhelming. That’s because spot glucose readings are messy. They jump around depending on food, stress, even sleep. You get a bit obsessed about numbers. Unless you have diabetes, tracking those changes doesn’t always lead to useful action. But a slowly changing number like HbA1c gives you a cleaner trend to watch.
If Garmin really can estimate this from your wrist, it could offer something that feels both simpler and more relevant. A check-in on whether your overall metabolic health is moving in the right direction.
What else Garmin could measure using this system?
Garmin’s patent focuses on glucose, but the same tech has other uses. It describes a setup with multiple light sources and detectors tuned to different wavelengths. That lets them measure how different compounds in the blood absorb light. The idea is that you get slightly different readings depending on what’s circulating in your system.
If you add more wavelengths, you can start estimating other things. Hydration levels, hemoglobin concentration, and possibly even things like stress-related changes in circulation. Some research groups have looked into using similar methods to estimate things like lactate or cortisol, though that’s still very experimental.
The point is, Garmin may not just be working on a glucose sensor. They might be building a platform. One that might eventually be able to pick up a whole range of slow-changing health signals.
So when could we see it?
It’s unlikely this will appear in any Garmin products during 2025. The sensor design described in the patent hasn’t shown up in any testing, firmware builds, or teardowns. If development is happening, it’s behind the scenes.
Late 2026 could be a possibility, but that depends on how far along they are. The patent includes detailed technical layouts, signal pathways and wavelength logic. But as we’ve seen with other companies, filing a patent doesn’t mean a product is coming. Apple has filed multiple patents for non-invasive glucose tracking, going back years, and none of them have turned into shipping hardware. Garmin could follow the same path.
That said, the hardware described in the filing is realistic. It would involve adding near-infrared light sources and matching photodetectors, arranged to detect subtle optical changes in tissue. It’s technically feasible with current materials and manufacturing techniques. But it would require a custom-built sensor module. Garmin certainly has the hardware and R&D muscle to make this happen.
The real challenge is reliability. Even if they avoid FDA clearance by marketing it as “informational only,” they’ll still need to test across skin tones, motion, temperature shifts and so on. If they’ve already started extensive real-world testing, then late 2026 might be feasible. If not, we’re probably looking further out.
Granted, with the rate of tech progress, it is only a matter of time before we get non-invasive glucose tracking from the wrist. Right now, the most we can say is that Garmin appears to be exploring this space. Whether that leads to a product in the near future will depend on engineering, validation and possible regulatory approvals.
I wouldn’t expect a full-blown glucose monitor from Garmin any time soon. But a wrist-based HbA1c trend estimate? That’s more realistic. And honestly, it might be more useful for most people anyway.
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