“What this work and work of others is doing is raising awareness that prolonged sitting, not TV [viewing] itself, is potentially detrimental to health.” —A/Prof Dunstan. Image: splityarnA NEW study has found more time spent watching television could have adverse effects on glucose homeostasis, increasing the risk for diabetes and cardiovascular disease.
The longitudinal study, currently accepted for publication in Diabetic Medicine, examined the television viewing habits and glycaemic measures of Australian adults five years after they took part in an Australian Diabetes, Obesity and Lifestyle study in 1999 and 2000.
Over the five years, participants reported their television viewing times had increased by about one hour per week on average.
After adjusting for factors such as changes in diet and physical activity, the researchers found significant increases in participants’ plasma glucose levels, resistance to insulin, beta-cell—pancreatic cells that store and release insulin—function, and fasting serum insulin levels.
Increased insulin secretion, a response to increasing insulin resistance in early stages of glucose intolerance, and other disturbances in glucose stability could be adverse indicators of diabetes risk, according to the research team.
The researchers then adjusted for participants’ waist circumference to factor out physiological changes possibly mediated by weight gain rather than by television viewing itself.
After the adjustment, an association with television viewing time was found in fasting serum insulin for women and 2-h (measured two hours after drinking a standardised glucose solution) plasma glucose for men.
ECU Health and Wellness Institute adjunct professor and Baker IDI Heart and Diabetes Institute researcher David Dunstan, who co-authored the study, says this unique finding was intriguing.
“We’re scratching our heads about what is contributing to the difference [in associated biomarkers] between men and women,” he says.
“Women [may be] better reporters of their television [viewing time], or it may relate to body compositional differences. I think it demands further research.”
According to the researchers, it is significant that even after making the possibly overcorrected adjustments these adverse physiological changes were associated with television viewing time and other sedentary behaviours such as playing video games.
The research team is currently expanding upon this observational study by taking a more interventional approach and comparing physiological changes in participants who decrease their sedentary behaviour with those who do not.
“What this work and work of others is doing is raising awareness that prolonged sitting, not TV [viewing] itself, is potentially detrimental to health,” A/Prof Dunstan says.
“We are now doing intervention research in a workplace context rather than a domestic context because prolonged sitting is a key characteristic of modern office workers.”
