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Public health strategies aimed at tackling obesity at a population level through lifestyle changes are more appropriate for preventing type 2 diabetes than targeted interventions based on an individual’s genetic risk, according to a study led by the Medical Research Council Epidemiology Unit at the University of Cambridge.

We need effective strategies in place if we are going to stem the rapid rise in the number of cases of type 2 diabetes

Nick Wareham

Over 380 million people worldwide are estimated to be affected by diabetes, with serious consequences for the health and economy of both developed and developing countries. Type 2 diabetes is thought to originate from a complex interplay of a large number of genetic risk variants and lifestyle factors, such as diet and exercise. Lifestyle interventions can reduce the risk of developing diabetes in high-risk individuals by 50%; however, whether there is value in targeted lifestyle interventions according to a person’s genetic susceptibility is unclear.

In an attempt to answer this question, a team of researchers led by the University of Cambridge studied 12,403 middle-aged individuals from the 340,234 person European Prospective Investigation into Cancer and Nutrition (EPIC) cohort who developed type 2 diabetes and a further control subset of 16,154 participants. The researchers calculated a genetic risk score for type 2 diabetes for these individuals based on which of 49 known genetic variants for the disease each person carried, and arranged the individuals into four equally-sized groups from lowest to highest genetic risk score. They then examined the combined effects of the genetic score and lifestyle factors on the development of diabetes. The results of the study, which was mainly funded by the European Commission under its Framework 6 programme, are published today in the open access journal PLoS Medicine.

The researchers found that the percentage of people of normal weight who developed type 2 diabetes over a ten-year period varied between 0.25% for those with the lowest genetic risk to 0.89% for those with the greatest genetic risk. In obese people, these figures ranged from 4.22% to 7.99%. In other words, obese individuals had the highest risk of developing type 2 diabetes regardless of their genetic risk score, emphasising the role of lifestyle as being much more important in the development of the disease than genetics.

Professor Nick Wareham, Director of the MRC Epidemiology Unit, says: “We have known for a long time that there is no one cause for type 2 diabetes – it’s a complex interaction of dozens of genes and our lifestyles. Recent genetic breakthroughs have provided the promise of targeted lifestyle interventions based on a person’s genetic make-up. However, genetic risk factors are greatly outweighed by lifestyle factors.

“We need effective strategies in place if we are going to stem the rapid rise in the number of cases of type 2 diabetes and the burden this places on our health systems. Our research suggests that focusing on tackling the lifestyle factors that lead to obesity at a population level will have a much greater impact than tailoring prevention strategies according to an individual’s genetic risk.”

Professor David Lomas, Chair of the MRC’s Population and Systems Medicine Board, adds: “One of the most effective ways to reduce the impact of type 2 diabetes is to stop people developing the condition in the first place, and this large international study reinforces the idea that broad promotion of a healthy diet and lifestyle is the way to go. Genomic information has already given us important insights into the diabetes disease mechanism, and grouping patients based on their genes and other biological factors still holds a great deal of promise for directing more targeted treatments for type 2 diabetes.”

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