"We are already seeing the early signs of adult-onset diabetes in five year olds," said professor Claude Marcus, head of the National Centre for Child Obesity in Huddinge, to Svenska Dagbladet.
"That means reduced sensitivity to insulin and evident effects on the blood vessels. It's very serious because Type-2 diabetes is an illness which affects the whole system."
This form of diabetes, which is non-insulin-dependent, is becoming increasingly widespread in developed countries.
Some 1.2 percent of children at the centre in Huddinge have been shown to have Type-2 diabetes. The first case of adult-onset diabetes in a Swedish teenager was recorded just two years ago.