By Mangai Balasegaram in Hanoi, Vietnam

Le Thu Quy is one of Asia's growing number of "lean diabetics"

Le Thu Quy could hardly be described as obese, even by standards in her native Vietnam.

At just 44kg and 1.47m tall, she looks an unlikely candidate for Type 2 diabetes, a disease associated with obesity and old age in developed countries.

Yet this petite, 48-year-old nurse is part of a growing and alarming trend in Asia, where diabetes is stretching across a wider range of age, weight and class than ever before.

The disease is even striking children. The youngest victim found in Vietnam is just 11 years old. Japan has a nine-year-old diabetic. And in Singapore, an epidemic of Type 2 diabetes in children sparked a government campaign, "Trim and Fit".

"Children are getting a disease that once only affected their grandparents or parents," said Dr Anil Kapur, Vice-Chairman of the World Diabetes Foundation (WDF), at an international diabetes summit in Hanoi, Vietnam.

The diabetes epidemic is exploding faster in Asia than in any other region in the world - and beyond previous predictions by experts.

The World Health Organization (WHO) says diabetes cases in Asia will rise by 90% in the next 20 years. The disease - and its related disorders - is set to become the 21st century's biggest health crisis.

"You're talking about 330 million people affected in the next 20 years. There is nothing like that with Aids or bird flu," said Paul Zimmet, Director of the International Diabetes Institute, in Victoria, Australia.

"Yes, you could have a bird flu pandemic. But with diabetes, you walk down the streets in Harlem [New York City] or Nauru now and you see people with motorized wheelchairs because of amputations, or people who have gone blind or going for dialysis."

In Hanoi, where people have switched from bicycles to motorbikes, diabetes has doubled Dr Gauden Galea, WHO

Asia already has the bulk of cases. It is home to four of the world's five largest diabetic populations - India, with 33 million cases, and China, Pakistan and Japan with 23, 9 and 7 million cases respectively .

The Pacific island of Nauru has the world's highest diabetes prevalence.

Even in some poorer Asian nations, diabetes rates are twice that of many European countries. For example, the prevalence in urban Cambodia, at 7%, is roughly equal to that in far-wealthier Australia.

LIfestyle changes

Genes are partly to blame. But changing eating patterns and physical activity are clearly driving the epidemic in Asia.

"In the past decade in Hanoi, where people have switched from bicycles to motorbikes, diabetes has doubled," said Dr Gauden Galea, Regional Advisor for Non-Communicable Diseases for WHO's Western Pacific Region.

"That rate of increase in HIV/Aids would cause panic in health circles."

Diet is also changing rapidly, with more people eating out and eating junk food. Some traditional foods prepared outside the home are also becoming less healthy.

Dr Galea cited studies from Ho Chi Minh City showing how chicken noodle soup (pho ga), a Vietnamese favourite, had 23% more calories when prepared in restaurants.

In New Delhi, where one in six children are overweight, adolescents eat out at an average of at least three times a week, Dr Kapur said.

In big Chinese cities, studies show about 20% of children aged seven and over are overweight.

A genetic cause seems to play a part in some Asians and Pacific Islanders. Studies show Indians carry certain genes that increase susceptibility to diabetes and lack genes that provide protection, said Dr V Mohan, director of the Madras Diabetes Research Foundation.

Dr Mohan urged governments to move quickly

Other studies show poor nutrition in pregnant women can lead to diabetes in both the child and mother many years later.

As a chronic disease, diabetes debilitates the body slowly and in a variety of ways.

"It affects every single organ system," said Dr Kapur.

The WDF, which supports local diabetes prevention projects in the region, is working to prevent two disastrous consequences of the disease for the poor - losing a limb or going blind.

There is still poor awareness, even among health workers, about a disease that was relatively rare 10 years ago, Dr Galea said.

Most of Asia is still hopelessly unprepared for this health crisis, which will inundate hospitals and strain healthcare budgets, doctors said.

"Hospitals in India are already feeling the pinch," said Dr Mohan.

Asian governments need to take action now, he said.