The number of very young children with diabetes has risen dramatically in 20 years, research suggests.

The number of children under five who have had the type 1 form of the condition diagnosed increased five-fold between 1985 and 2004, suggesting that the environment in which babies are brought up could have dire consequences for their future health.

The exact causes of type 1 diabetes are unknown, although there is evidence that it might be at least partly inherited.

But the number of under15s with the condition almost doubled during the course of the study to an average of more than four cases per thousand children. The researchers said that the rise was too steep to be linked purely to genetic factors and concluded that the environment must be playing a part.

Their findings lend further weight to the “hygiene hypothesis”, which links the rise in some illnesses to the inability of children’s immune systems to cope with infection because modern environments are too sterile.

The chances of developing type 1 diabetes, formerly known as insulin-dependent diabetes, are higher if a family member has the condition.

Type 1 is different from type 2 diabetes, which affects people later in life and is linked to life-style factors such as obesity.

Of the estimated two million diabetics in Britain, about 250,000 suffer from type 1, including at least 20,000 children of school age, according to the charity Diabetes UK.

Lauren Shehan, 10, from Walthamstow, northeast London, had diabetes diagnosed aged 3 after she became ill without warning and lapsed into a coma while on holiday with her parents in Majorca. The only child in her school with type 1 diabetes, she now injects herself with three doses of insulin a day and attends regular clinics every three months.

Her mother Ann, 39, said: “Lauren is a popular, happy girl who enjoys PE and doesn’t let her diabetes bother her. But she had a rough time with illness when she was younger, and hearing that it could be the result of the surroundings in which she was brought up is frankly shocking.”

The study, carried out by a team at the University of Bristol and funded by Diabetes UK, suggested that there was a 4.4 per cent increase each year since 1985 in the number of children in whom type 1 diabetes had been diagnosed.

Polly Bingley, who carried out the research and is due to present the findings to the Diabetes UK annual conference in Glasgow today, said: “The incidence of childhood type 1 diabetes has been shown to be increasing all over Europe, particularly in the very young.

“Although the chances of developing diabetes are still low and depend on the hand of cards someone is dealt in terms of genetics, the increase is very worrying and too steep to be put down to genetic factors alone. It must also be due to changes in our environment.

“This could either mean that we are being exposed to something new, or that we now have reduced exposure to something that was previously controlling our immune responses.” If the immune systems of babies were not challenged by infections in early life they might lose the ability to regulate themselves, and attack the body’s own insulin production system instead, Dr Bingley added.

Simon O’Neill, a spokesman for Diabetes UK, said: “The evidence of a steep rise of type 1 diabetes found in the underfives indicates that the peak age for diagnosis of the condition in the UK is becoming younger. Whilst 10 to 14-year-olds remain the largest group for diagnosis, the rise in cases found in children under five is worrying.”

Dr Bingley added: “The changes which cause diabetes may occur four or five years before symptoms are noticed, so the environment in which very young children are being brought up could have a serious effect on their future health.”

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