CHARM smart ring measures glucose & ketones via sweat

It is important to emphasize from the outset that the Continuous Health Analyzing Ring Module (CHARM), recently detailed in a scientific publication, remains strictly a research project at this point. Whether this technology will ever materialize in a commercial product remains entirely uncertain.

Significant limitations persist across multiple fronts. Its current battery life of around 12 hours is, in our assessment, a relatively minor concern compared to the analytical challenges. Unsurprisingly, peer reviews raised critical questions regarding the underlying measurement technology itself. Reviewers explicitly noted that CHARM requires validation across larger, more diverse cohorts to prove its reliability across varying blood glucose levels and hydration states. Ongoing calibration will also likely remain necessary. Both the reviewer comments and responses from lead researcher Professor Joseph Wang are publicly accessible (PDF).

Weighing just 5.1 grams with an outer diameter of 3 centimeters, CHARM tracks four biomarkers continuously. Instead of relying on optical sensors that shine light into subcutaneous blood vessels, the ring analyzes sweat. In principle, the sensor suite can measure glucose, ketones, ascorbic acid (vitamin C), uric acid, lactate, and alcohol. However, to prevent voltage drops, the ring is constrained to tracking four parameters simultaneously. Sweat is sampled passively—without dynamic pumping—using an integrated hydrogel, with parameters measured electrochemically and processed onboard.

These metrics could prove particularly valuable for patients with Type 1 diabetes, where continuous glucose tracking is critical. Simultaneous ketone monitoring offers additional clinical value, potentially enabling early detection of life-threatening diabetic ketoacidosis.

Note on the lead image: The image resolution was upscaled using AI without altering any substantive details.Detailed photos and technical diagrams of the ring are available on page 7 of the publication (PDF).