Type 2 diabetes gene link confirmed

British scientists have shown that a common genetic variation is linked to a two-fold increased risk of type 2 diabetes in UK men. A team based at University College London (UCL) says that carrying two copies of the TCF7L2 gene variant increases a person's risk of the condition by 100 per cent, whilst carrying one copy increases it by 50 per cent. This suggests that the impact of this gene on people's risk of developing type 2 diabetes is as great as that conferred by being clinically obese, says team leader Steve Humphries.

People with diabetes cannot regulate their blood sugar levels properly, either because their pancreas is not making enough insulin, or because the body becomes resistant to its effects. Type 2 diabetes usually affects people over the age of 40. It is more common in overweight, inactive people, and those with a family history of the disease, which suggests that genetic factors are also involved.

The TCF7L2 gene, which makes a protein involved in the control of blood sugar levels, was originally linked to type 2 diabetes by the Icelandic biotechnology company deCODE. This result was later confirmed in a large US study, and has now been shown to trigger the condition in the UK population too. The UCL team also looked at the gene variant in different ethnic groups, and found that the increased risk was the same in all of them.

The latest study involved a group of healthy, middle-aged men who were followed for 15 years. The results, published in the Journal of Molecular Medicine, show that around 40 pre cent of the population carry one copy of the gene variant, while 10 per cent carry two copies. 'Although being overweight is the major risk factor for developing diabetes, it is now becoming clear that an individual's genetic make-up has a big impact on whether or not they are going to develop diabetes', said Professor Humphries.

Professor Simon Howell, of Kings College London, said that TCF7L2 was 'the first gene that has really been shown to be generally applicable to the disease', adding that the latest study 'shows it is prevalent all over the world'. Dr Angela Wilson, of Diabetes UK, said that understanding why some people with certain genes are more likely to develop diabetes will help identify those at risk of the condition, 'with a view to enabling them to take preventative action by adopting a healthy diet, becoming active and ensuring they do not become overweight'.