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Weight outweighs genes as diabetes risk factor

New Delhi, May 21: Excess weight is a greater risk factor for diabetes than genes associated with the disease, a large international study has suggested amid an expanding market for genetic tests to predict the risk of diabetes.

The study has found that the cumulative incidence of diabetes is substantially greater in people with the lowest genetic risk who are overweight or obese compared to people who have normal weight but have the highest genetic risk.

“The public health message is that everyone should minimise the risk of diabetes through physical activity and a healthy diet,” said Nicholas Wareham, director of the epidemiology unit at the University of Cambridge School of Clinical Medicine who led the study.

Wareham and his colleagues tracked more than 340,000 people in eight European countries for over 11 years in the largest study so far to quantify the links between genetic factors and lifestyle factors with the risk of diabetes.

The researchers found that the absolute risk of a person developing diabetes is dominated by factors that can be changed, particularly obesity. Their study’s results were published in the journal PLOS Medicine on Wednesday.

Their findings emerge at a time when knowledge about genetic variations associated with diabetes has prompted several diagnostic companies in India to offer genetic tests to the public to predict the risk of diabetes. A New Delhi-based company which introduced a set of tests to assess the risk for diabetes three years ago says it gets about 3,000 requests each month from 150 locations across the country.

The new study has suggested that knowledge about genetic susceptibility to diabetes based on genetic variations linked to the disease identified so far have no implications for decisions about who should be targeted for intensive lifestyle modification.

The researchers looked for the presence of known genetic variants associated with diabetes, and assigned a higher risk to people who had a higher number of variants.

“There is no good evidence that the knowledge of these variants currently helps predict risk (of diabetes) nor in informing what action people should take,” Wareham told The Telegraph. “The currently known genetic variants don’t help personalise prevention.”

But, Wareham said, improved risk predictions could be possible in future as genetic knowledge accumulates.

Senior endocrinologists in India not associated with the study said they are not surprised by the results. Doctors have earlier cautioned that diabetes has been linked to multiple genes and their individual contributions to the disease remain unclear.

“I think such tests at this point in time are a waste of money,” said Anoop Misra, chairman of the Fortis Centre for Diabetes Obesity and Cholesterol, New Delhi. “Diabetes can be simply predicted by presence of obesity, family history, and age.”

A senior executive of a company that offers such genetic testing said people who sign up for diabetes tests are informed in advance that lifestyle factors are more important than genes in determining the risk of diabetes.

“We make it very clear that at no point can a genetic test be used as a stand-alone factor,” said Anubhav Anusha, managing director of a New Delhi-based biotechnology company that offers genetic testing for diabetes.

Doctors at the Indian Diabetes Research Foundation, Chennai had participated in an earlier component of the European study, looking at different responses to lifestyle modifications. “The impact of lifestyle modifications appears to override the effects of genetic variants thus far linked to diabetes,” said Ambady Ramachandran, head of the Indian Diabetes Research Foundation.