Although lifestyle has a huge--and perhaps the biggest--impact on someone developing Type 2 diabetes, researchers also believe a common gene variant could lead to the condition.

The new study followed healthy middle-aged men in the UK for 15 years, and found that carrying a common variant of the gene increased their risk of developing diabetes by 50 per cent. Carrying two copies of the variant gene increased the risk two-fold, to nearly 100 per cent. In the population as a whole, the impact of this gene on the risk of developing diabetes is as big as the problem of being clinically obese (having a body mass index over 30).

Professor Steve Humphries, of the UCL Centre for Cardiovascular Genetics, said: "Although being overweight is the major risk factor for developing diabetes, it is now becoming clear that an individual's genetic makeup has a big impact on whether or not they are going to develop diabetes.

"This is the first study that has followed healthy men and shown that carrying this risk gene has such a big effect. Because it is so common, and because the risk is so high, this gene seems to be causing as many cases of diabetes in the UK as obesity, which we know is the biggest risk factor.

"Our findings point to a whole new genetic mechanism which could be putting people at high risk of diabetes, and this needs to be explored. If we could understand more about this pathway, it could be possible to develop completely new treatment methods.

Although researchers are hopeful that further gene research will lessen the cases of diabetes, they still urge us to pay particular attention to diet and exercise.