Researchers build 4mm patch that monitors glucose from sweat, delivers drugs

By Jonah Comstock
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As exciting as the near future of diabetes management is, with numerous efforts underway to perfect closed-loop CGM and pump systems for automated insulin delivery, the systems of the future could be even easier. A paper out yesterday in Science Advances details the prototype for a 4 millimeter wearable patch that could not only noninvasively detect glucose levels from sweat, but also deliver the diabetes medication Metformin through microneedles in response to the sensor's readings.

"We present a wearable/disposable sweat-based glucose monitoring device integrated with a feedback transdermal drug delivery module," the 10 authors, affiliated with three South Korean universities, write. "The system provides a novel closed-loop solution for the noninvasive sweat-based management of diabetes mellitus."

The system has been built and tested on mice but has a long way to go before it's ready for human tests. But it's certainly a well-thought-out prototype that accounts for a lot of the traditional difficulties of testing blood glucose based on sweat. The tiny patch contains three glucose sensors to improve accuracy. It accounts for several factors that can confuse sweat-based sensors including pH, temperature, and the presence of drugs and other common biomarkers.

The microneedles that deliver the treatment drug are activated by heat, so the glucose sensor can trigger them with tiny chemical heaters. The actual calculations in the tested version still need to be run on a computer, so at least as of now it's not accurate to say the entire system fits on the tiny flexible sensor.

"For practical application of the current system, there are several things to improve," the authors write. "The long-term stability and uniformity of sensors are particularly important to make the system practically applicable to human subjects with minimum recalibrations. Further studies about the correlation between glucose levels of blood and sweat are needed before application to diabetic patients."

While glucose is the most concentrated and the most reliably readable in blood, it is also found in both sweat and tears, both of which would allow for a less invasive sensor than blood glucose requires. But there are a lot of hurdles in sensing glucose from these other fluids -- so many that when MobiHealthNews talked to experts from Dexcom, Glooko, and WellDoc a couple of years ago, they all agreed that the technology is not coming any time soon.

Yet research into the area continues. One high-profile investigation into this space is a partnership between Verily and Novartis subsidiary Alcon to create a contact lens that can detect glucose from tears. Additionally, last January researchers at Stanford University and the University of California-Berkeley detailed their own wearable sweat sensor in Nature, with glucose sensing listed as a possible application.Kobe 13 A.D. Shoes