Researchers at Penn State University have developed a new technology that can measure glucose through sweat instead of blood, eliminating the need for a needlestick.

Their advancement could be valuable to individuals with diabetes, who must monitor their blood sugar several times a day.

The low-cost, non-invasive device attaches to the skin and measures glucose levels within a matter of seconds to minutes, depending upon climate conditions, the amount of sweat excreted, and an individual’s pH levels.

How Does the Device Work?

Researchers started with laser-induced graphene (LIG), a material with high electrical conductivity. Because LIG is not sensitive to glucose, the team combined nickel, which is sensitive to glucose, and gold, to reduce allergic reactions to the nickel.

Finally, developers added a microfluid chamber, which allows the sweat to pass between the skin and the sensor, avoiding irritation to the skin.

Sweat or other biofluids can have varying pH, which affects the glucose reading, so researchers integrated another pH sensor with the chemical carbachol for calibrating the effect from pH. This way, the sensor can stimulate small, ongoing amounts of sweat, allowing the sensor to perform continuous glucose monitoring. Normal variations can incorrectly skew the results of your reading.

“With a carbachol sensor in place, you don’t need to worry about pH or sweat variation among people or weather,” Huanyu (Larry) Cheng, PhD, assistant professor of engineering science and mechanics at Penn State and researcher, told Verywell.

How Reliable Is Non-Invasive Glucose Monitoring?

Cheng admits this technology needs improvement before it is ready for widespread use. For instance, glucose can take several minutes to travel between blood and sweat, so non-invasive glucose monitoring is not a good option when immediate results are needed, such as in a diabetic emergency.

Mark Cucuzzella MD, FAAFP, professor at the West Virginia University School of Medicine, WVU Center for Diabetes and Metabolic Health, told Verywell via email that there are many potential advantages to non-invasive glucose monitoring.

“Non-invasive continuous glucose monitoring is the present and future of diabetes as well as pre-diabetes care,” Cucuzzella said. “People see the effects of foods on their blood sugar immediately and can make adjustments to stabilize it…Continuous glucose monitoring benefits anybody who has any issue with carbohydrate intolerance as they can tailor their eating and exercise to achieve stable normal blood sugars. It is also incredibly helpful when reducing diabetes medications safely.”

More testing is still necessary before non-invasive glucose monitoring becomes widespread.

“This technology is novel and needs further testing before it can replace interstitial fluid and the current continuous glucose monitors that are FDA approved,” Cucuzella said. “If the device is properly inserted and accurate, there really is no pitfall. The current continuous glucose monitors are small and non-invasive. There is no risk of infection or any adverse reaction to the monitor itself.”

Other Uses for Non-invasive Sweat Testing

As this technology improves, researchers are hopeful they can expand it to measure other common health indicators.

“We are really happy and excited about the result, not only for the glucose readings, but we will be able to extend the application to other biomarkers like cortisones, cytokines, sodium, potassium, and iron concentrations,” Cheng said.

Being able to rapidly measure some of these metrics can have many benefits. For example, rapidly measuring electrolytes like sodium and potassium could be valuable for athletes performing in warm weather. Measuring cortisone levels could help determine someone’s current stress response, and cytokine levels can be an indication of infection.