A newly released study challenges a 40-year-old theory that certain minorities are genetically prone to diabetes.

By analyzing genetic studies, a team of researchers found no evidence to support the theory suggesting that cycles of feast and famine in early human history created a gene to help the body use scarce nutrients -- which now leads to obesity and diabetes in sedentary modern lifestyles.

The study was conducted by Michael Montoya, a researcher at the University of California in Irwin and his Australian counterparts.

"Our study challenges the presumption that Native American, Mexican American, African American, Australian Aborigine or other indigenous groups are genetically prone to diabetes because the evidence demonstrates that higher rates of diabetes across population groups can be explained by non-genetic factors alone," Montoya said.

The study helps to explain why more than 250 genes have been studied as possible causes of type-2 diabetes, but together those genes explain less than 1 percent of the diabetes prevalence worldwide, the researchers reported.

"When it comes to diabetes, we're finding that genes are no more important for ethnic minorities than for anyone else," said Stephanie Fullerton, a population geneticist and bioethicist at the University of Washington and co-author of the study.

Existing gene studies fail to include controls that can explore the potential impact of social and environmental factors such as poverty, housing segregation or poor diet -- all stronger indicators of diabetes than genes, Montoya said.

"Our study shows that by focusing on genes, researchers miss the more significant and alterable environmental causes of diabetes," he said.

Montoya said that in order to gain a better understanding of the causes of type-2 diabetes, future research efforts will require interdisciplinary teams that assess social, historical and environmental factors as carefully as researchers have studied the genetic factors.

Yin Paradies, an epidemiologist at Australia's Menzies School of Health Research and another study co-author, said factors associated with poverty, such as poor diet, reduced physical activity, stress and low birth weight, all contribute to diabetes in minority groups.

The study found that it is virtually impossible for geneticists to define ethnicity and race in strictly scientific terms -- historic, political and social factors inevitably influence their definition of genetic groups, according to Montoya.

Source: Xinhua