A drug-free diabetes treatment? An implant lowers blood sugar in mice.

Researchers report that a wireless implant can clear excess sugar from the blood without drugs, added genes or living cells. In mice with both type 2 diabetes and obesity, the under-the-skin device returned high blood sugar to normal within 60 to 90 minutes of being switched on, according to the study published October 22 in Science. After six weeks, the treated mice had lost up to 10 percent of their body weight and had lower blood triglycerides, a type of fat.

The device is about 3 centimeters long. It contains a catalyst made of gold flakes and platinum particles on spongelike graphite. When powered with electricity, the catalyst converts glucose into gluconate, a compound the kidneys can more easily remove in urine. Martin Fussenegger, a bioengineer at ETH Zurich, noted that even experimental implants for diabetes still depend on insulin, which clears sugar from the bloodstream but does not remove it from the body.

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The system runs automatically. A wearable glucose monitor detects high blood sugar and sends readings to a smartphone, which switches the implant on. It switches off when levels return to a safer range. The automated setup ran for two weeks in eight mice. The catalyst could still convert glucose after up to three months under the skin, though the study did not establish how long the whole device would last.

The team suspects that with less glucose available for energy, the body turns to fat stores. In the mice, blood levels of chemicals released when fat breaks down, such as ketones, were higher. “This system kind of targets the root cause, which is the energy surplus by glucose in the body,” Fussenegger said.

It remains unknown how well the approach would work in people. David Klonoff, an endocrinologist at Sutter Mills-Peninsula Medical Center who was not involved, called it “a potentially promising method” but said the risks must be ruled out first. He pointed to possible gluconate buildup, which could upset the body's acid-base balance, and possible loss of electrolytes such as sodium and potassium. He also estimated that humans consume about 250 grams of carbohydrates daily, versus about two grams for mice, so a much larger implant or several devices might be needed. In a lab test, a larger device cleared nearly all glucose from about 5 liters of solution, though not a full day's intake. Fussenegger's team plans to test the device in pigs and sheep before considering human trials.