I got this from the diabetes UK website, something must be going badly wrong at the genetic or social level (in us or the food we eat) for situations like this to occur.

http://www.diabetes.org.uk/news/jan05/bigger.htm

Bigger but not better
Children as young as two are being diagnosed as obese and at high risk of Type 2 diabetes, says a new study.

The research looked at more than 100 obese children and found that a third of them already had insulin resistance, a condition closely linked to Type 2 diabetes.

The study, carried out at the University College London Hospitals, looked at children as young as two and up to the age of 18. As well as finding insulin resistance in some of the children, the study found that one in three had high blood pressure and a similar number had cholesterol abnormalities.

"This research only adds to the weight of evidence that obesity is leading to more and more cases of Type 2 diabetes in children," said Amanda Vezey, Care Advisor at Diabetes UK.

"Diabetes can lead to serious complications so it's essential that this trend is halted. Our children need more exercise and a healthier diet to ensure their weight doesn't put their health at risk."