(CNN)It’s a potentially fatal disease whose risks can in many cases be prevented through lifestyle measures. So why has diabetes seen a massive increase in sufferers?

The number of people living with the potentially fatal disease has quadrupled since 1980, to more than 400 million, according to the World Health Organization (WHO).

Worldwide, diabetes killed 1.5 million in 2012 alone, with high blood-glucose causing another 2.2 million deaths, the organization says.

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