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The sweat sensor measures blood glucose without a prick test

Researchers have developed a device that can measure glucose in sweat with a fingertip, a less painful alternative to finger pricks.

Many people with diabetes undergo multiple, painful finger pricks every day to measure their blood glucose. 

To prevent this, the device takes measurements from a person’s sweat with a fingertip and a personalized algorithm provides an accurate estimate of blood glucose levels. According to the American Diabetes Association, more than 34 million children and adults in the US have diabetes.

While self-monitoring of blood glucose is a critical part of diabetes management, the pain and discomfort caused by finger stick blood collection can keep people from testing as often as they should.

Scientists have developed ways to measure glucose in the sweat, but because the sugar level is much lower than in the blood, they can vary depending on the sweat rate and the properties of the skin. As a result, the glucose level in sweat usually does not accurately reflect the value in blood.

So to get a more reliable estimate of blood sugar from sweat, Joseph Wang of the Department of Nano engineering at the University of California, San Diego, and his colleagues wanted to devise a system that could capture sweat from a fingertip, measure glucose, and then correct for individual variability.

The researchers made a touch-based sweat glucose sensor with a polyvinyl alcohol hydrogel on top of an electrochemical sensor, which was screen printed on a flexible plastic strip.

When a volunteer placed his fingertip on the sensor surface for a minute, the hydrogel absorbed small amounts of sweat. Inside the sensor, glucose in the sweat underwent an enzymatic reaction that resulted in a small electrical current detected by a handheld device.

The researchers also measured the volunteers’ blood sugar with a standard finger prick test, and they developed a personalized algorithm that could translate each person’s sweat glucose into their blood glucose level.

In tests, the algorithm was more than 95 percent accurate at predicting blood glucose levels before and after meals, the researchers reported.

According to the researchers, a person with diabetes would only need a finger prick once or twice a month to calibrate the device.

But they added that before sweat diagnosis can help manage diabetes, experts need to conduct a large-scale study of the device.

The study “Touch-Based Fingertip Blood-Free Reliable Glucose Monitoring: Personalized Data Processing for Predicting Blood Glucose Concentrations” has been published in ACS Sensors.