Genetic variations that are linked to type 2 diabetes cannot yet help doctors to predict who is most likely to develop the disease, scientists have found.
While more than 20 DNA variants are now known to affect people’s risk of the condition, research has found that adding these to standard predictive tools does nothing to increase their accuracy.
The findings, from a team at University College London, suggest that commercial DNA tests that claim to assess disease risk based on genetic profiles are unlikely to be effective. For all the promise of genetic research, traditional means of identifying people at risk of diabetes are still more reliable.
The genetic links to diabetes found so far offer more insights into the biological pathways that cause the condition than they do into prediction, the scientists said.
In the study, funded by the British Heart Foundation (BHF) and the Medical Research Council, researchers used two standard scoring systems to assess more than 5,000 people for diabetes risk.
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These use factors such as age, body mass index (BMI), and family history of diabetes.
Both performed well, identifying between 20 per cent and 30 per cent of people who went on to develop the condition. Adding genetic information, however, made no difference. The results are published in the British Medical Journal.
The genetic data added little because the contribution they make to diabetes risk was probably already captured by including family history in the prediction tools, scientists said.
Professor Steve Humphries, who led the research, said: “Whilst genome-wide scans have now identified more than 20 genes involved in risk of type 2 diabetes their benefit for risk prediction is challenging.
“That absolutely doesn’t mean, however, that finding out which genes are linked to diseases is fruitless. These genetic clues could lead to major breakthroughs in understanding, preventing, treating and even curing these widespread diseases in the future.
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“For type 2 diabetes the major risk factor is being obese, particularly with a BMI over 30. The results don’t say that genes aren’t important, but simply that the major risk factor is becoming overweight, which is due in large part to eating too much compared to energy expenditure.”
Peter Weissberg, medical director of the BHF, said: “For the time being, I don’t believe that purchasing genetic tests to predict your susceptibility to type 2 diabetes or heart disease is a good investment and the BHF does not endorse the use of genetic home screening tests.
“The implications of the results of such genetic tests are still unknown, even to medical experts. ‘Conventional’ risk factors such as obesity, smoking, cholesterol and blood sugar levels remain the cornerstone of risk prediction, and can be measured during a trip to the GP.
“The most important message to people is to moderate their diet, maintain a good exercise programme and to avoid becoming overweight, and if they are overweight to lose weight slowly and steadily as this will reduce their risk, both of type 2 diabetes, and of heart and circulatory disease.”