Diabetes could threaten the existence of indigenous peoples around the world, experts have warned.
Western patterns of obesity are being seen in indigenous peoples
Scientists meeting at a diabetes conference in Melbourne heard such tribes faced extinction this century unless obesity was tackled.
Western diets and sedentary lifestyles are leading to obesity and a rise in Type 2 diabetes in Asia, the Pacific, Australia and the Americas.
But experts say if urgent action is taken, the trend could be reversed.
The three-day conference hopes to agree on a set of measures to present to the United Nations for an international effort to curb the epidemic.
There are up to eight million new cases of diabetes across the world each year.
It is predicted that around 250 million people will be affected by 2050.
Complications of Type 2 diabetes include increased risk of heart disease, stroke and kidney disease.
Type 2 diabetes - the form of the disease which usually develops in adulthood - already affects 50% of adults on the Pacific Island of Nauru which has a population of just 10,000.
Diabetes was unknown in the Pacific before WWII.
Rates are also high among Sioux and Pima Indians in the US, 45% of whom have the disease and the Torres Strait Islanders in northern Australia, where 30% are affected.
Professor Martin Silink, head of the International Diabetes Foundation, which was holding the conference, said indigenous peoples were at a greater risk of Type 2 diabetes because of their genetic make-up.
Canadian diabetes expert Professor Stewart Harris said diabetes posed a serious threat.
"The rapid cultural transition over one to two generations of many indigenous communities to a Western diet and sedentary lifestyle has led to diabetes replacing infectious diseases as the number one threat to their survival," he said.
Professor Paul Zimmet director of the International Diabetes Institute, said: "We are dealing with the biggest epidemic in world history.
"Without urgent action there certainly is a real risk of a major wipe-out of indigenous communities, if not total extinction, within this century.
"It could also mean the end of some of our treasured indigenous groups."
But he said: "It is a tragic situation, but not a lost one.
"The world needs to act now if we are to deal with this problem, which threatens to consume world economies and bankrupt health systems.