Scientists at the Royal Free Hospital say they have taken a major step towards finding a cure for Type 1 diabetes.

Following six years of research, the team believe they have discovered the cause of the condition, which results in the body being unable to produce the hormone insulin – something previously unknown.

This new research, published in the Journal of Clinical Investigation, means that an effective treatment could be developed more easily.

Prof Lucy Walker and her team at the Royal Free’s Institute of Immunity and Transplantation have found that a particular kind of immune cell, called a follicular helper T cell, is responsible for triggering an immune response in the body that leads to the destruction of insulin-producing cells.

Because these cells are destroyed by the body’s own immune system it cannot produce any insulin, the hormone that controls glucose levels in the blood and enables it to use glucose as energy.

Although scientists have known for some time that T cells cause diabetes, this is the first time the particular type of T cell has been identified.

However, Prof Walker said there is still a long way to go before a cure is developed because it is still unclear why these T cells cause insulin-producing cells to be destroyed.

“This is an important discovery,” she said. “Now we know that it is these T cells which set off a chain of reactions, leading to the destruction of insulin-producing cells.

“It means we are one step closer to developing an effective cure for Type 1 diabetes.

“However, everybody has these T cells and we still do not know why they expand in some people to cause diabetes while in other people they do not.”

There is currently no cure for Type 1 diabetes, a lifelong condition that causes a person’s blood sugar level to become too high. Patients are required to inject insulin whenever they eat to control their blood glucose levels. Almost 400,000 people in the UK have Type 1 diabetes, including 29,000 children.

The work was performed in collaboration with the clinical diabetes team headed by Dr Miranda Rosenthal. She said: “Type 1 diabetes is a growing problem and research that helps us understand how it develops will ultimately lead to better treatments for patients.”