Children who watch TV or use smartphones or tablets for more than three hours a day may be at a higher risk of developing diabetes, a new study has warned.
Daily screen time of three or more hours is linked to several risk factors associated with the development of diabetes in children, researchers said.
These include adiposity, which describes total body fat and, crucially, insulin resistance, which occurs when cells fail to respond to insulin, the hormone produced by the pancreas to control levels of blood glucose.
Researchers, including those at St George's, University of London, assessed a sample of nearly 4,500 9-10 year old pupils from 200 primary schools in the UK for a series of metabolic and cardiovascular risk factors.
These included blood fats, insulin resistance, fasting blood glucose levels, inflammatory chemicals, blood pressure and body fat. The children were also asked about their daily screen time to include TV, and use of computers and games consoles.
Boys (22 per cent) were more likely than girls (14 per cent) to say they spent three or more hours on screen time, as were African-Caribbean (23 per cent) kids compared with their white European (16 per cent) or South Asian peers (16 per cent).
Trends emerged between screen time and ponderal index - an indicator of weight in relation to height, and skin-folds thickness and fat mass - indicators of total body fat.
These levels were all higher in children reporting more than three hours of daily screen time than in those who said they spent an hour or less on it.
There was a strong trend between a daily quota of three or more hours of screen time and levels of leptin, the hormone that controls appetite; fasting glucose and insulin resistance.
The associations between screen time and insulin levels, insulin resistance, ponderal index, skinfolds thickness and fat mass remained significant even after taking account of potentially influential factors, such as household income, family background, puberty stage and physical activity levels.
"Our findings suggest that reducing screen time may be beneficial in reducing type 2 diabetes risk factors, in both boys and girls and in different ethnic groups from an early age," researchers said.
"This is particularly relevant, given rising levels of type 2 diabetes, the early emergence of type 2 diabetes risk, and recent trends suggesting that screen time related activities are increasing in childhood and may pattern screen-related behaviours in later life," they said.
The research was published in the journal Archives of Disease in Childhood.