Being a couch potato may not be a deadly as you think, say British and Australian researchers who ruled out sitting as a direct cause of diabetes. Their findings cast doubt on the popular saying that "sitting is the new smoking," and say their study indicates that several complex factors determine whether sitting is harmful to health.

"Sitting has attracted a lot of publicity in recent years for being as dangerous as smoking and for being harmful regardless of how physically active people are," said lead author Emmanuel Stamatakis of the University of Sydney. "However, this is one of the very few long-term studies to investigate whether there is a link between sitting behaviors and risk of development of diabetes."

Stamatakis and colleagues from the University of Exeter, University College London, and Victoria University, Australia, analyzed responses from a long-term health study of London-based office workers who were initially free of diabetes and major cardiovascular disease.

The participants, who were middle-aged and older office workers based in London, were asked in 1998 to detail the time they spent sitting, including at work and commuting as well as their leisure time and watching television.

Researchers then examined their blood glucose levels until the end of 2011 to determine how many had developed diabetes during the 13-year follow-up, taking into consideration several factors including obesity, physical activity, and alcohol and smoking habits.

They found little evidence for a link between sitting and diabetes, and these weak associations were limited to TV sitting time.

"Importantly, our research was among the first long-term studies to distinguish between various types of sitting behaviors — not just TV sitting, which is used in the majority of existing studies," said Stamatakis. "But TV time and sitting time are practically uncorrelated so we have very good reasons to believe that the health risks attributed to TV in the past are due to other factors, such as poorer mental health, snacking and exposure to unhealthy foods advertising," he said.

"Many previous studies also rarely acknowledge how higher BMI at the outset of the study increases the participant's risk of developing diabetes, which could compromise study results.

"Another reason for our results could be that these London-based workers were protected by the large amounts of walking they reported, which was nearly 45 minutes per day on average. With most white-collar workers forced to spend many hours each day in front of a computer not moving, this amount of physical activity may be an absolute necessity to maintain good health."

More than 29 million Americans have diabetes, and it's the seventh leading cause of death, according to the American Diabetes Association. More than a quarter of Americans age 65 and older have diabetes.

The study was published in the British Journal of Sports Medicine.