'Diabetes risk' for lateborn babies

Diabetes is an increasing risk as the mother gets older

First born children of older mothers are at greater risk of developing diabetes, say researchers.

Professor Edwin Gale and colleagues at Southmead Hospital in Bristol looked at 1,375 families in the Oxford area in which one or more child had diabetes.

They found that the mother's age at the time of delivery was strongly related to the risk that the child would go on to develop type one (insulin dependent) diabetes before the age of 15.

It appears some non-genetic factor is influencing the unborn child in utero

Dr Polly Bingley, Southmead Hospital, Bristol

The risk increased by 25% for each five years of the mothers' age, so that a 45-year-old mother was more than three times likely to have a child who developed diabetes than a 20-year-old mother.

To a lesser extent the risk of diabetes was also linked to older fathers.

Second children and their younger brothers or sisters were progressively less at risk of developing the condition.

Throughout the country women are in general having their children at an older age: between 1970 and 1996 the proportion of children born to mothers aged 30-34 years increased from 15% to 28%.

Diabetes increase

The authors of the British Medical Journal paper say: "The increase in maternal age at delivery in the UK over the past two decades could partly account for the increase in incidence of childhood diabetes over this period."

Researcher Dr Polly Bingley said the reason why the risk of diabetes fluctuated was unknown, and that further research was required.

Older mothers are known to have a higher risk of having babies with some conditions caused by damaged genes, but in this case there was no evidence of genetic abnormalities.

Dr Bingley told BBC News Online: "It appears some non-genetic factor is influencing the unborn child in utero.

"It may be an interaction between the mothers immune system and the developing immune system of the unborn child, or it may be due to changes in placental function as the mother gets older."

Dr Bingley stressed that type one diabetes was still a relatively rare condition, affecting 3.5 children in every 1,000.

A spokesman for the Diabetes UK said: "There has been an alarming increase in type one diabetes in recent years, and the problem is that we don't know why this should be.

"It could be possible that this is another piece in the jigsaw."

Type one diabetes occurs when the pancreas fails to produce sufficient levels of insulin, a hormone that helps to convert glucose into energy, or when cells are unable to use insulin produced by the pancreas, a condition called insulin resistance.

In its advanced stage, diabetes can cause serious damage to the eyes, nerves, gums, kidneys and blood circulation, potentially leading to death.

However, the condition is usually combated quite easily by injections of manufactured insulin.