One of the largest genetic studies ever undertaken has discovered nine new genes linked to type 2 diabetes, opening a door to new understanding and possible treatment.

Scientists from 174 research centres around the world, who studied the genes and blood glucose level of more than 120,000 volunteers, were able to identify a set of genes that control the body's response to glucose in the blood.

It is hoped the discovery could lead to new treatments for diabetes, which affects more than 220 million people worldwide. Ninety per cent of those have type 2 diabetes, also known as late-onset diabetes because it typically develops later in life.

It occurs when the tissues of the body become resistant to the effects of insulin, needed to regulate glucose. Sufferers may control the disease with diet and exercise but often have to take drugs and in more serious cases have to inject insulin.

Jim Wilson, a geneticist from Edinburgh University who heads the Scottish cohort study, said: "This is an incredibly important finding. The discovery of these new genes influencing blood-sugar levels is the first step on the important journey to developing new therapies for diabetes.

"It opens up a whole new area of research to find which proteins are 'druggable'. Genetics is like a can-opener: it allows us to get inside and understand what's going on."

The hope is that in five to ten years scientists will be able to pinpoint which individuals are genetically susceptible to developing type 2 diabetes, and that there will be a drug available which can prevent its onset. "What we have found may not contribute to personalised medicine becoming a reality today, but it will contribute to it happening tomorrow," Dr Wilson said.

The nine new genes include those that influence blood sugar levels and also the first gene influencing levels of insulin. A subset of the genes was associated with diabetes itself.

Dr Wilson said the biological pathways that the genes highlighted were those involved in the control of blood sugar and might point to novel drug targets for glycaemic control. The pathways included not only glucose transport and sensing and pancreatic cell development, but also circadian rhythms and fatty acid metabolism.

To find out which genes are involved in glucose control, the team studied the genes of 50,000 healthy volunteers, also measuring glucose. It then sought to replicate the findings in approximately 75,000 more people.