Risk of developing type-2 diabetes is high if you are 'overweight and not active'
10 June 2014 Last updated at 13:46 BST
More than a third of adults in England are on the cusp of developing type-2 diabetes.
A report, in the British Medical Journal, highlights an "extremely rapid" rise in pre-diabetes since 2003.
The authors predict a surge in type-2 diabetes in the coming years, with consequences for life expectancy and disability.
Health correspondent Dominic Hughes reports.