Nanoengineers at the University of California, San Diego have tested a temporary tattoo that both extracts and measures the level of glucose in the fluid in between skin cells.

The temporary tattoo, which is a flexible, easy-to-wear device, could be a promising step forward in noninvasive glucose testing for patients with diabetes. Researchers said the sensor is a "proof-of-concept" tattoo that could pave the way for the Center to explore other uses of the device, such as detecting other important metabolites in the body or delivering medicines through the skin.

At the moment, the tattoo doesn't provide the kind of numerical readout that a patient would need to monitor his or her own glucose. But this type of readout is being developed by electrical and computer engineering researchers in the Center for Wearable Sensors.

The research team is also working on ways to make the tattoo last longer while keeping its overall cost down.

Presently the tattoo sensor can easily survive for a day. These are extremely inexpensive--a few cents--and hence can be replaced without much financial burden on the patient," researcher Amay Bandodkar said in a statement.

The NanoEngineering Department and the Center for Wearable Sensors at the Jacobs School of Engineering at UC San Diego "envisions using these glucose tattoo sensors to continuously monitor glucose levels of large populations as a function of their dietary habits," Bandodkar said.

Data from this wider population could help researchers learn more about the causes and potential prevention of diabetes, which affects hundreds of millions of people and is one of the leading causes of death and disability worldwide.

People with diabetes often must test their glucose levels multiple times per day, using devices that use a tiny needle to extract a small blood sample from a fingertip. Patients who avoid this testing because they find it unpleasant or difficult to perform are at a higher risk for poor health, so researchers have been searching for less invasive ways to monitor glucose.

A similar device called GlucoWatch from Cygnus Inc. was marketed in 2002, but the device was discontinued because it caused skin irritation, researchers noted. Their proof-of-concept tattoo sensor avoids this irritation by using a lower electrical current to extract the glucose.

Their findings are detailed in the journal Analytical Chemistry.