A new device may one day save those with diabetes from the frequent finger-pricking and cumbersome external monitors required to check glucose levels–by instead keeping tabs from inside their torsos. In a study published online today in Science Translational Medicine, researchers report that an implantable glucose sensor has worked in pigs. Ultimately, clinical trials and FDA approval will determine if the device holds any promise for humans, but researchers say this animal test is an important first step.

“You can run the device for a year or more with it constantly working, and recording glucose quite satisfactorily. Now, we are focused on getting the human clinical trials going. We hope to begin the first human trial within in a few months,” said [lead author, David Gough.] “If all goes well with the human clinical trials, we anticipate that in several years, this device could be purchased under prescription from a physician,” said Gough.[University of California - San Diego]

As Popular Science reports, the device is “just a bit smaller than a Double-Stuf Oreo”–around 1.5 inches wide and half an inch thick. Gough and colleagues implanted the device in two pigs: one for 222 and and another for 520 days. It works by monitoring oxygen consumed in a chemical reaction with the enzyme glucose oxidase–the amount of oxygen consumed is proportional to the amount of glucose in the user’s blood. Though some already use similar sensors, none have lasted this long.

The authors say that short-term glucose sensors already exist, but they need to be replaced every 3-7 days and haven’t been approved by the Food and Drug Administration as a “primary standard for glucose measurement”.[Nature]

The device can make up for variations caused by exercise and surrounding scar tissue doesn’t seem to affect its readings. It relays glucose levels wirelessly to a data recorder about the size of a cellphone.

“Continuous glucose monitors are very helpful, but the key thing is that you have to wear them, and that’s a big challenge for many people,” says Aaron Kowalski, research director for the Juvenile Diabetes Research Foundation’s [a co-sponsor of the study] artificial pancreas project. He notes that, because current devices are still slightly conspicuous and require vigilance, teenagers and young adults are less likely to wear them. “So the idea of having a one-year sensor that is implanted is very, very appealing” [Popular Science].

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Image: C. BICKEL/SCIENCE TRANSLATIONAL MEDICINE