Hui Won Yun; Seoul National University
MORE than 300 million people around the world have type 2 diabetes. For many of them, an insulin kit is an indispensable daily accessory. Being caught without it or forgetting to use it after meals could be fatal. Could slapping on a smart patch bring peace of mind?
A team in South Korea thinks so. It is developing a wearable device to keep diabetes under control. The patch, shown below, is made from graphene and senses glucose in sweat. It is connected by wires to a portable electrochemical analyser. When blood sugar is too high, it releases the drug metformin through microneedles to lower it.
Graphene is thin and flexible, making it comfortable to wear on the skin. When the device is worn, the microneedles pierce the skin, reaching the subcutaneous tissue. At 250 micrometres in diameter and 1 millimetre high they are too small to cause pain.
To release metformin when it is needed, the patch switches on a tiny heater embedded within. This dissolves a coating on the microneedles so that they release metformin.
Tests in diabetic mice showed that the patch is effective at sensing high glucose levels, releasing an appropriate dose of metformin and lowering blood sugar. It was also tested on two healthy men, showing that its glucose measurements are accurate and correlate well with blood concentrations (Nature Nanotechnology,).
The work is still in its early stages, but the team hopes to make the patch suitable for everyday human use. “We need to reduce the cost and increase the reliability of the sensors over a longer period of time,” says Dae-Hyeong Kim at Seoul National University in South Korea.
“A non-invasive device that promises the end of finger prick glucose tests and injections is the aim“
Treatment for type 2 diabetes usually starts with diet and exercise, moves on to metformin, and then insulin injections when the condition gets more severe. A non-invasive device that combines glucose monitoring and drug delivery is the ultimate aim, says Richard Guy at the University of Bath, UK, promising an end to finger prick glucose tests and injections. The patch is a big step towards that goal, he says. “The fact that someone’s put that all together into a wearable system that’s not ridiculously clunky is quite significant.”
But it’s some way from being a complete solution. One problem is that the doses of drug needed in humans are too big to be delivered by the patch, says Guy. “Even with a device that makes holes in your skin to poke it through, I have a hard time figuring out how it’s going to work.”
The patch shows that monitoring glucose through the skin is feasible, either in sweat or by other approaches such as extracting molecules across the skin, which Guy is working on. “My guess is it may take another five to 10 years,” says Guy.
Meanwhile, Kim and colleagues are investigating better ways to deliver metformin through the skin. Closing the loop with drug delivery is likely to take even longer, however.
This article appeared in print under the headline “Smart patch for diabetes”
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