The number of adults with diabetes has quadrupled worldwide in under four decades to 422 million, and the condition is fast becoming a major problem in poorer countries, a World Health Organization study showed.

In one of the largest studies to date of diabetes trends, the researchers said ageing populations and rising levels of obesity across the world mean diabetes is becoming "a defining issue for global public health".

Type 2 diabetes is a long-term condition characterized by insulin resistance. Patients can manage their diabetes with medication and diet, but the disease is often life-long and is a major cause of blindness, kidney failure, heart attacks, stroke and lower limb amputation.

"Obesity is the most important risk factor for type 2 diabetes and our attempts to control rising rates of obesity have so far not proved successful," said Majid Ezzati, a professor at Imperial College London who led the WHO research.

Published in The Lancet journal ahead of the United Nations World Health Day on April 7, the study used data from 4.4 million adults in different world regions to estimate age-adjusted diabetes prevalence for 200 countries.

It found that between 1980 and 2014, diabetes has become more common among men than women, and rates of diabetes rose significantly in many low and middle income countries, including China, India, Indonesia, Pakistan, Egypt and Mexico.

Margaret Chan, the WHO's director-general, said the findings showed an urgent need to address unhealthy diets and lifetsyles around the world.

"If we are to make any headway in halting the rise in diabetes, we need to rethink our daily lives: to eat healthily, be physically active, and avoid excessive weight gain," she said in a statement from the WHO's Geneva headquarters.

"Even in the poorest settings, governments must ensure that people are able to make these healthy choices and that health systems are able to diagnose and treat people with diabetes."

The study found that northwestern Europe has the lowest rates of diabetes among women and men, with age-adjusted prevalence lower than 4 percent among women and at around 5 to 6 percent among men in Switzerland, Austria, Denmark, Belgium and the Netherlands.

No country saw any meaningful decrease in diabetes prevalence, it found.

The largest increases in diabetes rates were in Pacific island nations, followed by the Middle East and North Africa, in countries like Egypt, Jordan and Saudi Arabia.

The data also showed that half of adults with diabetes in 2014 lived in five countries - China, India, the US, Brazil and Indonesia. Rates more than doubled for men in India and China between 1980 and 2014. – Reuters