Garmin patent hints at glucose tracking from the wrist

A recently published Garmin filing with the US Patent Office doesn’t just mention glucose tracking. It describes in detail how it could actually work. Tucked inside a broader system for analysing exercise data, it lays out a technical path toward non-invasive blood sugar monitoring.

Glucose isn’t the headline of the patent and perhaps this is why no-one has picked up on it. But it’s more than just a throwaway reference if you take the time to actually read through the document. The description goes well beyond listing it as a possible bio-signal. It outlines a specific way glucose could be measured using a technique called pulse spectrometry.

In simple terms, this involves shining light, particularly in the near-infrared range, into the skin and measuring how that light is absorbed or reflected. Because glucose affects the optical properties of tissue and blood, changes in those signals can reveal underlying shifts in blood sugar levels. The patent describes an array of light emitters and photodetectors, each tuned to different wavelengths, working together to pick up those subtle differences.

The glucose connection

What is actually outlined is a method to estimate HbA1c. This is meaningful if you’re trying to understand long-term metabolic health. Most wearables don’t go near this space. So the fact that Garmin’s patent includes detailed logic and equations for estimating glycated hemoglobin using multi-wavelength PPG signals deserves attention.

The approach is based on analysing the AC and DC components of PPG signals at different wavelengths. From that, the system could infer concentrations of oxygenated hemoglobin, deoxygenated hemoglobin, and critically, glycated hemoglobin, which is what HbA1c is. The processor would then estimate a user’s average blood glucose levels over a period of months, not minutes.

That’s a bit different compared to traditional spot-check blood glucose readings or continuous glucose monitors (CGMs). It implies the wearable could track long-range trends. One could easily imagine a new Garmin metric – that tracks your average HbA1c over time.

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In fact Clinicians use HbA1c to diagnose and monitor type 1 and type 2 diabetes. It’s especially useful because it doesn’t depend on short-term changes, like what you ate that morning. A healthy level of glycated hemoglobin is typically below 5%. A level above 7% or 10% (depending on the individual’s circumstances), present a concern for developing diabetes. Knowing your HbA1c could help you make lifestyle changes and track how they’re affecting your long-term metabolic health.

The bottom line

All of this shows the company isn’t just speculating. They’ve built in the optical theory, sensor setup, and signal processing required to make it plausible. Even if this never ships, the patent reflects serious engineering effort.

Non-invasive glucose tracking using light has been a goal in wearable tech for years. What stands out here is Garmin putting this into a published document, along with enough detail to show they’ve thought through the hardware side and how the data would be processed.

Now, let’s be clear. This is a patent application, not a product announcement. Apple, for example, has a range of patents for glucose monitoring none of which have made it into the Apple Watch. However, seeing Garmin lay out a system that could potentially measure a marker like HbA1c from the wrist is certainly thought-provoking. The ability to non-invasively track long-term glucose trends would be a big step forward for wearable tech.

If such a feature were to be realised, it could offer users a convenient way to keep an eye on their metabolic health over time. The patent itself states that “it would be of great benefit to users of a wrist-worn device…to determine a glycated hemoglobin level or receive general feedback on the overall health of the user on the determined glycated hemoglobin level”. That’s a fair point. Getting HbA1c usually means a blood test, so having it on your wrist would be incredibly useful.

***This article first appeared on Gadgets & Wearables, where the story was originally reported.

Note: Source details withheld to preserve the originality of our reporting. We always credit official disclosures when appropriate, and link to other media when they are the original source of a story.

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