Britain faces an "accelerating epidemic" of childhood diabetes, with diagnosis in under-fives set to double by 2020, researchers report today.
A review of trends in 17 countries in Europe shows that the rise is so rapid that environmental changes must lie behind it. Doctors believe these include the increase in Caesareans, reduced exposure to infections in early childhood and bottle feeding.
Type 1 diabetes is a disorder of the immune system in which the insulin-producing cells of the pancreas are destroyed. Insulin is an essential hormone without which the body cannot use glucose (sugar) and diabetics require daily injections of insulin to control their blood sugar levels.
Researchers analysed trends from 20 European centres and identified 94,000 cases of Type 1 diabetes in children aged under 15 in 2005. Extrapolating the rate of growth from 1989 to 2003, they estimate the total will grow by 70 per cent to 160,000 by 2020.
In the under-fives, the growth is even more rapid – from 3,530 to 7,142, an increase of 102 per cent.
Chris Patterson, from the Queen's University, Belfast, who led the study published in The Lancet, said hypotheses had been advanced to explain the increase in diagnosis but none had been proved: "We don't have any certain explanation of what is going on. But a few studies have given pointers.
"Exposure to infections in early life has been associated with a reduced risk of diabetes. Some studies have suggested that if you send your children to pre-school groups [where they are more likely to get infections from other children] they have a lower risk. The notion is that it is good to get the immune system primed early in life. If it is not exercised early, it could have an adverse reaction later to some exposure we don't know about."
Studies have indicated a 20 per cent higher risk of Type 1 diabetes in children born by Caesarean, probably because babies delivered vaginally collect microbes from the birth canal that are important to the development of their immune systems.
"Kids born by Caesarean have altered microbes in their gut – and what happens in the gut is important in the development of the immune system," Dr Patterson said.
Rapid weight gain after birth is linked with a higher risk of Type 1 diabetes and is more often seen in bottle-fed babies. Breast feeding is believed to be protective. For unknown reasons, older mothers are also thought to be at higher risk of having babies who will develop the condition.
The authors said that the earlier the condition starts in an individual, the more likely they are to develop complications in later life, such as kidney and circulatory problems, leading to renal failure, amputations and blindness.
In Britain, the number of under-15s with Type 1 diabetes is predicted to rise from 3,527 in 2005 to 5,185 in 2020. The number of cases in under-fives is projected to rise from 701 to 1561.