The Korean research team used a substance called graphene to develop a thin, flexible patch. Graphene conducts electricity, and can be transparent, soft and very thin, the researchers explained.
The patch also contains a variety of sensors that detect humidity, sweat glucose levels, pH and temperature, the researchers said. In addition, the patch contains heat-sensitive microneedles.
The patch uses sweat to determine “sweat glucose,” which can be used to figure out blood glucose levels. Lee said the accuracy of the sweat glucose sensor is similar to that of home blood glucose meters in the United States.
Guy pointed out that someone who sweats a lot might pose a challenge for the patch.
But the researchers said they’ve already taken this into consideration. “We integrated a humidity sensor in the diabetes patch to check how much sweat is generated. So the person who perspires heavily wouldn’t affect the sensing,” said Tae Kyu Choi, another study author from Seoul National University.
Likewise, Choi said, the researchers accounted for someone who perspires very lightly.
The researchers tested the glucose-sensing ability of the patch in two humans and found the device was able to accurately measure blood sugar levels.
In the current version of the patch, the researchers used microneedles to deliver the diabetes drug metformin to mice. Over six hours, the drug — delivered through the skin — was able to drop blood sugar levels from 400 milligrams per deciliter to 120 milligrams per deciliter, the researchers said. For someone without diabetes, a normal blood sugar level taken randomly would generally be under 125 milligrams per deciliter, according to the U.S. National Library of Medicine.
Insulin — the hormone necessary to lower blood sugar for people with type 1 diabetes — wasn’t used because it’s a protein that would be difficult to deliver through microneedles because it’s large, and it would be vulnerable to the heating process that allows the drug to be delivered through the skin, the study authors explained.
But, Guy said he expects that should this system go forward in development, other drugs that can lower blood sugar more effectively might be considered. “I think metformin was chosen as an example of a drug used in diabetics for the illustration of proof-of-concept,” he said.
The researchers said they believe the device could be used by either type 1 or type 2 diabetics.
However, Dr. Joel Zonszein, director of the Clinical Diabetes Center at Montefiore Medical Center in New York City, said the cost of the device might make it very impractical for people with type 2 diabetes. And, he said, people with type 2 diabetes don’t have to know what their blood sugar levels are as often as people with type 1 diabetes.
“They have proved the concept — that a sweat patch can do the monitoring and can deliver a drug transdermally [through the skin]. Trying to do something like this noninvasively really is the holy grail of diabetes. So, there may be a future for this, but there are many barriers to be overcome,” Zonszein said.
The researchers said their next step is to improve the long-term stability and accuracy of the blood glucose sensor. Lee and Choi estimated it would be at least five years before they could solve any remaining obstacles and commercialize the device.
“The promise of a transdermal, minimally invasive glucose monitoring device is coming closer to fruition. I’d hope we’d see a new effort to bring a skin-based monitoring device for glucose to the market in the next few years,” Guy said. “In contrast, such as system combined with drug delivery is, in my opinion, much further away.”