Genetic testing to see someone’s predisposition to type 2 diabetes is not significantly better than an assessment based on traditional risk factors for the disease, such as weight, blood pressure and blood sugar levels, two new studies show.

One of them, published in the Nov. 20 issue of The New England Journal of Medicine, was led by diabetes researcher James B. Meigs, MD, MPH, of Massachusetts General Hospital and an assistant professor of medicine at Harvard Medical School. He and his colleagues looked for 18 diabetes-related genetic variants in blood samples from just over 2,300 participants in the Framingham Heart Study. The participants were followed for 28 years, during which time 255 developed type 2 diabetes. Each participant was assigned a genotype score, based on the number of genetic variants he or she had. Then, the researchers compared the predictive value of this score to traditional risk factors for the type 2 diabetes such as obesity as measured by body mass index, age, blood pressure, cholesterol, fasting glucose and triglyceride level. They found that screening for these genetic variants did predict who would develop diabetes, but not significantly better than a regular doctor’s examination.

“Although genetic information appeared to be useful when only factors known in youth were considered, genetic information in the context of risk factors measured in adulthood did not help to refine the prediction of diabetes risk. Our findings underscore the view that identification of adverse phenotypic characteristics remains the cornerstone of approaches to predicting the risk of type 2 diabetes,” the study says.

The second study was led by researcher Valeriya Lyssenko, MD, of Sweden's Lund University and colleagues who looked for 16 diabetes-associated genetic variants in blood samples taken from close to 19,000 residents of Sweden and Finland. The study participants were followed for an average of 23 years. During this follow-up, 2,201 (almost 12 percent) developed type 2 diabetes.

Traditional risk factors were found to be strong predictors of diabetes in this study as well. On the other hand, the identification of the genetic variants responsible for diabetes had only a small impact on the ability to predict the disease.

However, the findings do not mean that genetic information will never be helpful in predicting who is at risk of diabetes and should take preventive measures, Dr. Meigs said.

“It’s really in the situation where you don’t know very much about risk factors, for instance in youth, where the genetic information might be the most informative.”

He also added that the genetic testing might be of great help in persuading people to have a healthier lifestyle in order to prevent diabetes. Studies in patients with genetic factors putting them at risk of Alzheimer’s disease had shown the information was crucial in inducing lifestyle alterations.