Genetic tests are no better at predicting an individual's risk of developing type-2 diabetes than conventional assessments based on family history and physical factors such as blood pressure and weight, according to a new study by US scientists.
The research team, led by Dr. James Meigs of the General Medical Division at Massachusetts General Hospital in Boston, analyzed medical data from over 2,300 volunteers that had been followed over a 28-year period as part of a study into cardiovascular disease. Of these individuals, 255 developed type-2 diabetes during the study period. The researchers looked for the presence of 18 different gene variants associated with type-2 diabetes and scored each individual's likelihood of developing the disease based on the particular combination of genes they carry. They then compared this to a risk assessment based on the detailed medical records of each participant, which documented family history of diabetes, weight, cholesterol, blood pressure and blood sugar levels. They found that although their gene-scoring system was a good measure of the risk of diabetes, it was no more accurate or useful than traditional methods of physical examination.
These findings were supported by a second study carried out in Sweden and Finland, led by Dr. Valeriya Lyssenko of Lund University, Sweden, which followed nearly 19,000 participants, 2,201 of whom developed diabetes, over an average of 23 years. They compared the presence of 16 gene variants linked with diabetes with physical risk factors and reached a similar conclusion to the American researchers.
Type-2 diabetes is a major health burden worldwide, and affects around two million people in the UK. There are around 25 gene variants that are linked with an increased likelihood of developing the disease. A simple genetic test to identify those most at risk is an attractive prospect. However, the outcome of these two studies indicates that we do not yet have the understanding to implement such a test. Dr Meigs commented: 'With our current knowledge, the measurements your [doctor] makes in a standard check up tell you what you need to know about your type-2 diabetes risk, and genetics doesn't tell you much more'. Nonetheless, he remains hopeful for the future, adding: 'as additional risk genes are discovered, the value of genetic screening is likely to improve'.