For years, the idea of checking glucose without inserting a sensor under the skin has felt just out of reach. Now, researchers in California have taken another step towards that future with a smart ring capable of measuring glucose, ketones and several other biomarkers continuously from sweat.
The prototype isn't designed to replace today's continuous glucose monitors (CGMs), but it does offer a glimpse of where wearable health technology could be heading over the next decade.
Image credit: David Baillot/UC San Diego, Jacobs School of Engineering.
A ring that measures more than activity
Engineers at the University of California San Diego have developed what they describe as the first fully integrated smart ring capable of continuously monitoring multiple biochemical markers using sweat collected from a finger.
Unlike today's smart rings, which primarily record heart rate, sleep and activity, this device measures molecular biomarkers including:
- Glucose
- Ketones
- Vitamin C
- Lactate
- Uric acid
- Alcohol
All of the sensing hardware, battery, electronics and wireless communications are built into the ring itself, with results transmitted to a smartphone app. The work has been published in Nature Communications.
No exercise needed
One of the most interesting aspects of the technology is that users do not need to exercise to produce sweat.
Instead, the researchers use an osmotic hydrogel that gently draws tiny amounts of sweat through the skin continuously. That sweat is then analysed by miniature electrochemical sensors inside the ring.
The system also develops personalised calibration factors over time, helping interpret changes in an individual's biomarker levels rather than relying on one universal reading.
Why glucose and ketones together matters
For people living with Type 1 diabetes, glucose only tells part of the story.
Ketones become critically important during illness, prolonged high glucose or insulin interruption, helping identify when diabetic ketoacidosis (DKA) may be developing.
Today's CGMs monitor glucose alone. Ketones still require a separate blood test.
Being able to monitor both continuously has long been one of the biggest ambitions in diabetes technology.
Abbott has already signalled this direction through Libre Duo, its combined glucose and ketone sensor, which received CE marking earlier this year. Dexcom has also spoken publicly about future multi-analyte sensing platforms beyond glucose.
This smart ring approaches the challenge differently by measuring biomarkers in sweat rather than using a sensor inserted beneath the skin.
How accurate is it?
This is where expectations need to remain realistic.
The researchers report that glucose readings from the ring closely followed trends seen on commercial CGMs, while ketone measurements closely tracked commercial blood ketone meters during testing involving healthy volunteers and people with Type 1 diabetes.
However, "closely tracked" does not necessarily mean identical.
At this stage the work represents an early research prototype rather than a medical device ready for clinical use.
Independent validation, much larger studies and regulatory approval would all be required before a product like this could ever be considered as a replacement for established diabetes technology.
Could this replace a CGM?
Probably not any time soon.
Modern CGMs have benefited from decades of development and are trusted to guide insulin dosing, hybrid closed-loop insulin pumps and hypoglycaemia alerts.
Those systems require exceptionally high levels of reliability because treatment decisions depend on them.
A sweat-based wearable faces additional scientific challenges, including differences in sweat production, hydration, skin conditions and how sweat chemistry changes between individuals.
For now, this research should be viewed as proof that continuous biochemical monitoring may eventually extend well beyond glucose rather than evidence that sensor-free glucose monitoring has arrived.
The bigger picture
The most exciting aspect of this research may not be glucose at all.
Wearables are steadily evolving from tracking movement and heart rate towards measuring what's actually happening chemically inside the body.
Researchers are increasingly exploring continuous monitoring of inflammatory markers, hormones, metabolites and multiple biomarkers simultaneously to build a richer picture of metabolic health.
If that vision becomes reality, future wearables may help people understand illness, recovery, nutrition, exercise and diabetes in ways that today's devices simply cannot.
Love My Libre's view
Research like this shows how quickly wearable technology is evolving, but it also highlights how far ahead today's CGMs already are.
For people relying on insulin, glucose readings must be accurate enough to make treatment decisions every minute of the day. That is an incredibly high bar, and one that decades of CGM development have only recently achieved.
The future is unlikely to be a choice between a CGM or a smart ring. Instead, different technologies may sit alongside one another, each measuring different biomarkers and providing a broader understanding of health.
For now, this smart ring is an exciting piece of research rather than the next device you'll be wearing.
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