Publishing their findings today in the Journal of the American Medical Association, the US scientists report that study participants with diabetes, as well as those without diabetes and higher fasting blood sugar levels, were more likely to develop cancer or to die from cancer.
The findings will fuel mounting evidence of the detrimental impact obesity, now considered an epidemic, has on health. About 300 million people worldwide are believed to be obese and a further 750 million overweight, a physical state increasingly associated with an elevated risk of life-threatening conditions, notably heart disease and diabetes.
Far from diminishing, the numbers of children who are overweight is set to rise from 20 per cent to 25 per cent by 2008, according to market analysts Datamonitor.
The study authors at the Johns Hopkins Bloomberg School of Public Health and Yonsei University in Seoul, Korea concluded that glucose intolerance may be one way that obesity increases cancer risk and that the rising obesity rates may increase future cancer rates.
"This study provides more information on glucose intolerance, an emerging cause of cancer. It points to increased cancer risk as another adverse consequence of rising obesity around the world,"concluded Sun Ha Jee, lead author of the study.
The researchers had set out to provide further insight into previous research that suggested having diabetes or an elevated glucose level may increase cancer risk.
"The evidence has been mixed and many of the studies to date were relatively small," said Jonathan Samet, co-author of the study.
The scientists carried out a 10-year study of 1,298,385 Korean men and women, aged between 30 and 95 years old. Study participants provided information on their lifestyles and medical histories. Fasting blood samples were taken at biennial medical examinations.
The risk of developing cancer was comparable to the risk of dying from cancer. The group with the highest fasting glucose levels (greater than 140 mg/dL) had higher death rates from all cancers combined, report the researchers.
In men, the strongest associations were for pancreatic cancer; significant associations were also found in men for cancers of the oesophagus, liver and colon/rectum. In women, the strongest links were to cancers of the liver and cervix.
The authors noted that the study participants were substantially leaner than the typical Western population.
In a bid to tackle the fat epidemic the food industry, encouraged by consumer groups and government, is now constantly rolling out food and beverage products with a healthy profile.
Labelling, advertising, salt reduction and vending machines in schools all figured in a seven point manifesto launched in September 2004 by the UK's €99.58 billion food and drink industry. Portion sizes will be cut as the food giant's signatories, including Cadbury Trebor Bassett, Coca-Cola and HJ Heinz, aim to get to grips with the sensitive food and health debate.