An interesting development that points to the fact that lifestyle does also contribute to type 1 diabetes.
The number of under-fives in Europe with type 1 diabetes is set to double between 2005 and 2020, say experts.
The researchers, from Ireland and Hungary, warn cases in older children will also rise substantially.
Writing in The Lancet, they say genetics alone cannot account for the rapid rise, and suggest lifestyle factors are likely to play a role.
The study is based on 29,311 cases of type 1 diabetes recorded in 20 European countries between 1989 and 2003.
The researchers say the increase in type 1 diabetes has been so rapid that it cannot be blamed on genetic factors alone.
They also point out that the highest increases have been seen in Eastern Europe, where lifestyle habits are changing more rapidly than in richer Western European nations.
Researcher Dr Chris Patterson said: "The children of older mums are at slightly increased risk of type 1 diabetes as are children born by Caesarean section and children with rapid weight gain early in life, while breast-fed children are at slightly decreased risk.