Malnutrition promotes a form of diabetes distinct from those already categorized, concluded global experts on this pathology in an article published Thursday, emphasizing that poor countries are the first to be affected.

"We call on the international diabetes community to recognize this particular form of the disease," say the authors of this article published in the Lancet Global Health, which relays a consensus reached within the International Diabetes Federation.

The two main forms of diabetes are type 1, which appears in young people, and type 2, in older people. The first, which manifests itself acutely, results from an insulin deficiency; in the second, more common, the hormone is produced normally but the body is less sensitive to it.

However, experts are finding that a common form of diabetes does not fit into these categories. It appears in young patients, often under thirty, but is less acute than type 1 diabetes, with only reduced insulin production.

And, unlike type 2 diabetes, being overweight does not appear to be a risk factor. On the contrary, patients are generally malnourished or undernourished, with a lower than normal weight.

"It is estimated that 25 million people worldwide have this diabetes," mainly in poor or developing countries, the authors report.

This concept is not new: in the 1980s and 1990s, the World Health Organization did classify "malnutrition-related diabetes." But it abandoned this classification in 1999, due to a lack of agreement among experts on the fact that malnutrition is a sufficient factor to cause diabetes on its own.

However, since then, multiple studies - in Bangladesh, Ethiopia, India, Indonesia, Nigeria, Uganda, Pakistan, Rwanda - have confirmed the distinct existence of such a mechanism, according to the authors.

It is still largely unknown what physiological processes cause this diabetes, or how best to treat it: weight loss is logically not indicated and the effect of traditional treatments based on metformin or insulin remains uncertain.

Above all, the fight against this diabetes largely depends on maintaining and accelerating programs against poverty and hunger, in particular by "increasing access to simple, inexpensive, nutritious and protein-rich foods," the authors conclude.