A watch that tracks your pace, sleep, and recovery may soon take things a step further. Garmin is developing technology designed to estimate long-term blood sugar levels—right from your wrist—without the need for needles or invasive skin sensors.
From Heart Rate to Blood Sugar: What Garmin Really Wants to Measure
Sports watches have made us accustomed to tracking heart rate and blood oxygen saturation (SpO2). However, Garmin’s latest patent filings (No. US-20260033750-A1 and US-20250134464-A1) show the company is aiming much higher: analyzing the chemical composition of blood directly through the skin of the wrist.
The key parameter here is not a real-time glucose spike, but glycated hemoglobin (HbA1c). This indicator reflects the average blood sugar concentration over the last three to four months, providing a broader and more stable picture of metabolic health than a single “here and now” measurement.
For runners and health-conscious individuals, this is a significant distinction. HbA1c does not react sharply to a single meal or a heavy workout, making it better at reflecting long-term trends. Patent documentation suggests Garmin aims to achieve this using multi-wavelength PPG sensors that analyze how different light wavelengths are absorbed and reflected by the blood. Notably, an HbA1c level below 5% is considered a benchmark for good metabolic health.
Equally important is what this technology doesn’t require. Unlike current solutions, the watch would not need external CGM sensors, such as Dexcom patches, which currently only sync data to Garmin displays. The entire process would happen within the watch casing, using a light transmitter and receiver on the underside. For those with prediabetes, this could mean monitoring without pain or skin irritation.
How Light “Peeks” at Blood Under the Skin
The foundation of the proposed solution is pulse spectrometry—a method that distinguishes blood components based on how they react to light. The patent describes an array of LEDs emitting light in several ranges, including 500 to 1000 nm.
Different forms of hemoglobin—oxygenated, deoxygenated, and glycated—absorb light differently. This allows the watch’s processor to compare signals reflected from the blood and estimate the percentage of HbA1c in the total hemoglobin. Put simply: the watch “sees” how many glucose molecules have permanently bonded to red blood cells.
Interestingly, the documentation also mentions the potential to detect rarer forms of hemoglobin, such as carboxyhemoglobin or methemoglobin. These parameters can affect the body’s ability to transport oxygen and, consequently, an athlete’s performance.
Documents from May 2025 also describe the role of algorithms that account for user characteristics, such as age and body weight. The system is designed to use at least three optical signals to separate actual data from “noise.” This is crucial because skin and fat tissue on the wrist significantly scatter light, making precise measurement difficult.
Why Watch Strap Fit Matters for Accuracy
One of the biggest hurdles for wrist-based optical measurements is the watch itself. A strap that is too tight compresses blood vessels, altering blood flow and distorting readings. Garmin dedicated a significant portion of the patent to this issue.
The proposed solution involves a Pressure Metric Value (PMV) and a Pressure Compensation Factor (PCF). The watch will “sense” how tightly it sits against the skin by analyzing the PPG waveform. If the algorithm detects that vessels are overly compressed, it will automatically correct the result to ensure the HbA1c estimate remains reliable.
The software is also expected to account for anatomical differences between users, ranging from ligament structure to bone density. This represents a move toward personalized measurement rather than a “one-size-fits-all” algorithm.
Another innovative idea is the use of two light receivers placed at different distances from the transmitter. This allows the watch to analyze signals from different tissue “depths.” Such double-verification is intended to reduce errors caused by arm movement during running or temperature changes affecting blood flow to the skin.
The Race for Wrist-Based Sugar Tracking
Non-invasive glucose monitoring is currently one of the greatest challenges in the wearables market. Huawei already offers a “Diabetes Risk Study” feature in the Watch GT 6 Pro, but its approach is different. Instead of measuring a specific chemical parameter, the watch analyzes data over several days to estimate general diabetes risk.
Garmin is targeting more precision, aiming to provide a specific diagnostic value in the form of an HbA1c percentage. This is a more ambitious and potentially more useful approach.
While Apple and Samsung are also working on similar solutions, reports from 2025 suggest their technologies are still far from a market debut. By publishing two patents in quick succession, Garmin is signaling that metabolic health is a core pillar of its future development.
Experts note that focusing on HbA1c might be more realistic than attempting real-time glucose tracking. Long-term trends are simply easier to capture with optical sensors than sudden post-meal sugar spikes. This could allow Garmin to offer a reliable early-warning tool sooner than its competitors.
When Will This Tech Reach Garmin Watches?
It is important to remember that a patent does not guarantee an immediate product launch. Such advanced measurement will require new-generation sensors, more powerful processors, and highly refined software. This suggests the feature may only appear in future generations of flagship models.
For runners and recreational athletes, non-invasive HbA1c monitoring would represent a completely new approach to diet, training, and recovery planning. The ability to track how daily choices impact metabolic health—without lab visits—is an attractive prospect for everyone from those with health concerns to those seeking marginal performance gains.
While the technology is still being perfected, the direction is clear. Using light to “look” under the skin is one of the most promising paths to eliminating needles and test strips. If these patent promises become reality, a new indicator of actual health could soon appear on watch screens right next to VO2 Max.
The Future of Metabolic Health on the Wrist
Garmin’s patented method for estimating HbA1c using pulse spectrometry could be one of the biggest steps toward painless health prevention. If the technology successfully passes medical certification, sports watches will take on a whole new role: tools that don’t just record activity, but help us spot the early warning signs of lifestyle diseases.
