Scientists are developing a smart tattoo that could tell diabetics when their glucose levels are dangerously low. Once perfected, the tattoo will allow glucose levels to be monitored round the clock, and could allow an alarm system that would warn the diabetic if their glucose levels were to fall dangerously. A pain free testing system has been something of a holy grail for many years Diabetes UK It would also mean that diabetics would no longer have to subject themselves to the finger-prick devices that currently they must use every day. The tattoo has been designed Gerard Cote, of Texas A&M University, and Michael Pishko, of the chemical engineering department at Penn State University. It is made of polyethylene glycol beads that are coated with fluorescent molecules. Because glucose displaces the fluorescent molecules, the level of fluorescence is high when bodily glucose levels are low. Fluorescence levels could be measured using a device, such as a watch, that could also give users a readout of their glucose level. Cell fluid Preliminary studies in tattooed rats that have been given injections of glucose have yielded promising results. Regular tattoos consist of ink particles that are taken up by the cells in the skin. In this case, polymer molecules are injected under the skin using a needle. Because the molecules are slightly bigger than ink particles, they do not enter the cells but remain in the interstitial fluid that surrounds them. Dr Cote said: "This is important because the level of glucose in the interstitial fluid is directly related to blood glucose; whereas the glucose inside the cells would be nearly non-existent because it is almost immediately converted to energy." The abdomen or arm would be the most suitable places to have this tattoo, because being a fluorescent-based device; constant exposure to the sun would have to be avoided. Significant step A spokesman for the charity Diabetes UK said: "People with diabetes need to test their blood glucose levels on a regular basis and for most people this means pricking their finger to draw blood. "A pain free testing system has been something of a holy grail for many years and there are a number of new products which may provide that. "This smart tattoo uses a similar approach to a watch device which is currently available but takes it a step further. "The tattoo is still in the early stages of development but we look forward to seeing further test results." See also: 24 May 00 | Health 'Wristwatch' to monitor diabetes 14 Nov 01 | Health Pain 'prevents diabetics checking health' 23 Jul 02 | Health Poor literacy puts diabetics at risk Internet links: Diabetes UK Texas A&M University Penn State Chemical Engineering Chemistry and Industry The BBC is not responsible for the content of external internet sites Top Health stories now: Heart risk link to big families Back pain drug 'may aid diabetics' Congo Ebola outbreak confirmed Vegetables ward off Alzheimer's Polio campaign launched in Iraq Gene defect explains high blood pressure Botox 'may cause new wrinkles' Alien 'abductees' show real symptoms Links to more Health stories are at the foot of the page.