Turning into a couch potato with long hours of television viewing and a concomitant lack of exercise could significantly increase the chances of diabetes among adolescents, says a new study.

The research, conducted at the University of Sydney, suggests that teenagers the risk of diabetes could be three times more amongst teenagers who are hooked to television and junk food. Dr. Louise Hardy and his team gathered blood samples from 500 Grade-10 students as part of the study.

The tests revealed that boys who watched television and played computer games instead of engaging in physical activity were three times more prone to diabetes than their counterparts who indulged in physical activity.

Teenage boys who watched television for more than two hours a day were found to be far more susceptible to developing insulin resistance. Insulin resistance is a precursor to type-2 diabetes. Ninety per cent of boys and 75 per cent of girls in the study spent more than the recommended the two-hour guideline watching TV.

Some of the surveyed teens spent a total of almost 22 hours glued to their televisions and computers every week, the researchers noted. Boys were the worst offenders. "Girls have started to adopt screen technology, particularly Facebook and blogging," Dr Hardy was quoted as saying in the Daily Telegraph. The findings will be presented at the International Congress of Obesity in Sweden.

Diabetes is caused by a problem in the way our body makes or uses insulin. Insulin is needed to move blood sugar (glucose) into cells, where it is stored and later used for energy. Amongst diabetics, the fat, liver and muscle cells fail to respond to insulin in a normal fashion as a result of which blood sugar does not get stored in cells.

When sugar cannot enter cells, abnormally high levels of sugar build up in the blood. This is called hyperglycemia. High levels of blood sugar often trigger the pancreas to produce more and more insulin, but it is not enough to keep up with the body's demand.