The number of young children with early-onset diabetes has soared dramatically in the past 20 years, according to figures released by researchers today.
A study found that cases of type 1 diabetes among under-fives increased fivefold between 1985 and 2004, with one in 1,000 now affected by the disease.
The figures suggest more than 3,000 pre-school age children are affected by type 1 diabetes, compared with about 600 20 years ago.
The increase among under-fives was accompanied by a doubling of cases among children under 15 over the same period. The increase has mystified doctors who believe it has happened too rapidly to be caused by genetic factors, such as parents with diabetes passing it on.
"It's too fast to be genetic. It's got to be some sort of environmental influence, something these children are being exposed to, or something they're no longer exposed to that had a protective effect in the past," said Polly Bingley, a diabetes specialist at Southmead hospital in Bristol.
"In the past 20 years there has been an awful lot of changes in babies' diets, with less breastfeeding and changes in the age at which people introduce solid foods. That's where we've got to look for the cause of this," she added.
Type 1 diabetes is the less common of the two main forms of the disease, accounting for between five and 15% of all cases. It is caused by an inability of the body to produce natural insulin to control blood sugar levels, but unlike type 2 diabetes, it is not caused by lifestyle factors such as poor diet, lack of exercise and obesity. The soaring rates of the disease have been mirrored by studies in other European countries, but scientists have yet to pinpoint the reason. Other than changes to babies' diets, researchers are also investigating whether exposure to childhood infections, or conversely too sterile an environment, is causing changes in children's immune systems that may ultimately trigger the disease.
Diabetes can be distressing for children because treatment requires daily injections of insulin that must be continued for the rest of their lives.
It can reduce life expectancy by causing heart and kidney disease, stroke, blindness and nerve damage. "It's worrying because diabetes is a lifelong condition which unfortunately still has some long-term problems," said Prof Bingley, who is due to present the research at Diabetes UK annual conference today.
The study followed people living in Oxfordshire, Berkshire, Buckinghamshire and Northamptonshire. Over the 20-year period, incidence of type 1 diabetes rose 2.6% every year among the under-15s.
Symptoms of type 1 diabetes usually come on quickly, within a few weeks, beginning with severe thirst, frequent urination and weight loss. Later symptoms include tiredness, blurred vision, itching and slow healing of wounds.
Prof Bingley said it was too early to advise parents on how to reduce their children's risk of developing the disease.
"The whole focus of our research programme is working towards the possibility of being able to prevent it at some stage in the future, but in order to do that we need to know what triggers it," she said. Simon O'Neill of Diabetes UK said: "Whilst 10-14 year-olds remain the largest group for diagnosis, the rise in cases found in children under five is worrying."
