Malnutrition causes unrecognised type of diabetes: experts

But diabetes researchers have been tracking another form of the disease, which often appears in people aged under 30. It also affects insulin production but is less severe than type 1.

And rather than being linked to being overweight or obese like type 2, it affects people who are underweight because they do not eat enough.

A paper published in medical journal The Lancet Global Health shows that more than 25 million people suffer from this "type 5 diabetes", mostly in developing countries.

"We call upon the international diabetes community to recognise this distinct form of the disease," the authors wrote, reflecting a consensus reached by the International Diabetes Federation earlier this year.

The experts settled on calling this form of diabetes type 5, though types 3 and 4 have not been officially recognised.

Diabetes driven by malnutrition is not a new discovery -- in the 1980s and 1990s, the World Health Organization classified a form of "malnutrition-related diabetes". 

But the UN agency abandoned this classification in 1999 due to a lack of agreement among experts about whether undernourishment alone was enough to cause diabetes. 

Since then, numerous studies in countries including Bangladesh, Ethiopia, India, Indonesia, Nigeria, Uganda, Pakistan and Rwanda have indicated that this is possible.

The exact link between malnutrition and this strand of diabetes remains unknown. The efficacy of existing diabetes treatments that do not focus on weight loss on type 5 is also unclear.

The best way to fight the disease involves supporting programmes already working to combat poverty and hunger, the authors of the paper said.

This includes giving people access to "low-cost, energy-dense staple foods high in protein and complex carbohydrates" such as lentils, legumes, oil-enriched cereals and fortified grains, they added.

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