LONDON, Sept 10 (Reuters) - Half of all people of South Asian, African and African Caribbean descent living in Britain will develop diabetes by age 80, scientists said on Monday in research which also points to an alarming future for rates of the disease in Africa and Asia.
In the first study to reveal the extent of ethnic differences in the risk of developing type 2 diabetes, researchers said it seems a "Westernised" lifestyle of urban living with a poor diet and a lack of exercise could prove "toxic" for many British blacks and Asians.
The study, which tracked 5,000 Londoners for more than 20 years, found that by age 80, twice as many South Asian, African and African Caribbean men and women had developed diabetes compared with Europeans of the same age.
This means that approximately half of all South Asians, Africans and African Caribbeans in Britain will develop the disease by age 80 compared with only one in five of European descent, the researchers said.
"I think people underestimate the size of the problem," said Mike Knapton of the British Heart Foundation (BHF), who was not involved in the study but commented on it at a briefing in London. "This is a huge number of people...and it causes a significant problem both for the individuals themselves and for the health service."
Type 2 diabetes is a long-term condition characterised by insulin resistance that affects around 2.9 million people in Britain and, according to the World Health Organisation (WHO), more than 310 million people worldwide.
In the UK, an estimated 11.9 billion pounds ($19.1 billion) a year is spent on treating diabetes and its complications which include heart attacks, strokes and kidney disease and blindness.
Health experts have known for some time that people of South Asian, African and African Caribbean descent in Britain are at higher risk of becoming diabetic in mid-life, but they were not clear why, or whether the extra risk continues as people age.
URBAN ENVIRONMENT IS "TOXIC"
For the study, published in the journal Diabetes Care, researchers led by Nish Chaturvedi at Imperial College London looked at people aged between 40 and 69 who did not have type 2 diabetes, and from 1988 recorded those who developed the disease.
The team found that while Africans, African Caribbeans and Europeans tend to be diagnosed at around the same age of 66-67 years, South Asian men were five years younger on average when diabetes was diagnosed, meaning they are at even greater risk of complications.
The study also found that people who have increased resistance to the effects of insulin, as well as those who carry fat around the middle of the body when they are middle-aged, are at higher risk of developing the disease.
The researchers said their findings suggested the higher rate of diabetes in some South Asian and African Caribbean women is due to greater rates of obesity and higher resistance to insulin, which helps the body process sugar.
Chaturvedi said diets rich in high-calorie foods, combined with lifestyles which include little physical exercise, were the main factor behind the increased rates. "The urban environment is a toxic environment," she told the briefing.
Therese Tillin, also from Imperial, said the findings highlighted "astonishingly high risk of diabetes in middle-aged people in our ethnic minorities" and should serve as an early warning for countries in Asia, Africa and the Caribbean for what might come as populations adopt Westernised, urban lifestyles.
A WHO report in May showed rates of chronic diseases like diabetes and heart disease are already rising fast in poorer regions such as Asia and Africa as lifestyles and diets change.
($1 = 0.6240 British pounds) (Reporting by Kate Kelland, editing by Diana Abdallah)