Diabetes Forecast

Is The CGM of the Future a Penny-Sized Patch?

By Andrew Curry , ,

Sumita Pennathur, PhD
Photograph by Elena Zhukova

Sumita Pennathur, PhD

Professor of mechanical engineering at the University of California–Santa Barbara


American Diabetes Association Research Funding
Pathway Visionary Award

Sumita Pennathur, PHD, has spent her career designing very, very small things: aircraft the size of a coin, tubes 100 times smaller than a human hair, tests for diseases that require just a drop of blood. She earned degrees in aerospace engineering from the Massachusetts Institute of Technology and in the field of microfluidics from Stanford University, worked for Lockheed Martin and Sandia National Laboratories, and was awarded a Presidential Early Career Award for Scientists and Engineers.

But Pennathur, now a professor at the University of California–Santa Barbara, was plagued by a feeling that the problems she was solving were, well, small—until the day in 2015 when her then 4-year-old daughter was diagnosed with type 1 diabetes. “It was almost a calling,” Pennathur says. “I switched all my research to find something that could help her.”

In the years since, Pennathur has pivoted her lab toward developing technologies that will improve the lives of people with diabetes, particularly in the area of glucose monitoring. She’s focusing on continuous glucose monitors (CGMs), devices that measure changes in glucose using a sensor inserted under the skin. CGMs are a big improvement on frequent finger pricks because they provide glucose readings in real time.

But the devices have some major shortcomings, especially for young patients, as Pennathur learned after one was prescribed for her daughter. “The sensor has to stay in her body for days, it takes two hours to start up and get a reading, she still has to do finger pricks, and she gets made fun of at school,” Pennathur says. “Those things are not OK for my daughter.” And a CGM is expensive, costing up to $4,000 a year to maintain.

Pennathur’s involuntary crash course in CGM technology prompted her to launch an effort to build a continuous glucose monitor that’s fast, reliable, painless, and, above all, tiny. “It should be easy to build a device that looks like a Hello Kitty sticker—something the size of a penny you wear for a day that replaces finger sticks and is cheaper than anything else out there,” she says.

In 2017, Pennathur was awarded a five-year Pathway Visionary Award from the American Diabetes Association to support her quest to develop a painless, disposable glucose-monitoring patch. “It’s a high-risk, high- payoff project,” she says. “It’s never been done before, but by my calculations it can work.”

Pennathur’s expertise in micro- and nanochannels gave her the inspiration to build the device using needles that don’t penetrate far enough under the skin to trigger the nerves that signal pain. “It can be painless and doesn’t cause any infection,” she says.

The microneedles (too small for a red blood cell to fit inside) would dip into the interstitial fluid, the liquid that surrounds the body’s cells and the same fluid current CGMs use to monitor glucose levels. The device would use a small amount of fluid—“a million times less than a finger prick,” Pennathur says—to measure the level of glucose in the body. The materials and production costs would be cheaper, too.

Pennathur doesn’t plan on stopping with revolutionizing the CGM. The engineering professor has a separate project funded by the JDRF to develop a compact insulin pump, which she envisions about as thin as a playing card. She also plans to expand her research to other projects relevant to diabetes.

“When my daughter was diagnosed,I wanted to do anything and everything,” Pennathur says. Though she felt like a newcomer to the field of diabetes at first, she soon realized that her past work gave her the expertise she needed to make a contribution. “My lab and I have exactly the tools needed to address this problem. It’s a big undertaking, but we have the right team, and we know we are going to succeed.”

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