A wireless implant that clears excess sugar from the blood could someday offer a drug-free way to treat type 2 diabetes and obesity.
In mice with both conditions, the under-the-skin device brought high blood sugar back to normal within 60 to 90 minutes of being switched on, researchers report October 22 in Science. After six weeks, the treated mice lost up to 10 percent of their body weight and had lower triglycerides, a type of fat in the blood.
Diabetes affects about 830 million people worldwide. Conventional type 2 diabetes treatments like insulin and GLP-1 drugs require careful dosing. Even experimental diabetes-controlling implants still rely on the hormone insulin, which clears sugar from the bloodstream but doesn’t rid the body of it, says Martin Fussenegger, a bioengineer at ETH Zurich. The new implant instead removes glucose from the body without added drugs, genes or living cells.
The 3-centimeter-long device contains a catalyst made of gold flakes and platinum particles on spongelike graphite. When electricity powers it, the catalyst converts glucose into gluconate, a compound that is easier for the kidneys to flush out in urine. With less glucose available for energy, the body may turn to its fat stores instead, Fussenegger and colleagues suspect. In mice, that shift showed up as higher blood levels of chemicals released when fat breaks down, such as ketones. “This system kind of targets the root cause, which is the energy surplus by glucose in the body,” Fussenegger says.
The implant works like an automatic sugar-removal system: A wearable glucose monitor detects high blood sugar levels and sends readings through a smartphone that switches the implant on. When levels return to a safer range, it switches off. The automated system ran for two weeks in eight mice. The catalyst itself remained able to convert glucose after up to three months under their skin, though the study didn’t establish how long the entire device would last.
And it’s still unknown how well the device would work in people. “This is a potentially promising method,” says David Klonoff, an endocrinologist at Sutter Mills-Peninsula Medical Center in Burlingame, Calif., who was not involved in the study. “But the risks are significant and must be carefully ruled out before it can be safely tested on humans.”
Researchers need to determine how much gluconate the kidneys can clear, Klonoff says. If it builds up, it could disrupt the body’s acid-base balance, causing symptoms such as nausea or confusion; excreting it could also deplete electrolytes such as sodium and potassium, he notes.
Scaling up the device is another challenge. Humans consume about 250 grams of carbohydrates daily, compared with two grams for mice, Klonoff estimates. Meeting that demand could require a much larger implant or multiple devices, he says. In a lab test, a larger device cleared nearly all glucose from about 5 liters of solution, roughly an adult’s blood volume, though not a full day’s glucose intake.
Fussenegger’s team plans to test the device in pigs and sheep before considering human trials. If proven safe and effective, it could offer an alternative to existing diabetes treatments and a new weight-loss option for people regardless of whether they have diabetes, he says.
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