Findings are based on an analysis of the eating patterns of 200,000 men and women over long period
Globally, about one in nine adults have diabetes, and the disease will be the seventh leading cause of death by 2030
Researchers who analysed data of 1,153 people aged 18-69 years found those who ate 100g of chocolate a day had reduced insulin resistance and improved liver enzymes
A major new report by WHO has warned that diabetes cases have risen to 422 million in 2014 from 108 million in 1980