Patients with type 1 diabetes who received an experimental stem-cell treatment have been able to go as long as four years without needing insulin, researchers say.

Stem-cell transplants have effectively “reversed” the condition and freed a small group of patients from the need to have daily injections to control their condition.

Type 1 diabetes, also known as “insulin-dependent” diabetes, occurs when the body loses the ability to produce enough insulin to regulate blood sugar levels. Distinct from type 2 diabetes that is associated with obesity, it is usually diagnosed in childhood and typically requires lifelong insulin therapy in the form of injections or pumps.

But patients given a transplant of stem cells made from their own bone marrow have regained the ability to produce the vital hormone, and have managed to cease their insulin injections for an average of two and a half years, the authors report in the Journal of the American Medical Association.

Richard Burt, of Northwestern University, Chicago, and colleagues said that twenty of twenty-three patients became insulin-free — twelve continuously and eight transiently — for periods as long as four years. The transient group of eight had to restart insulin at reduced levels. The short-term benefits of the therapy were first reported two years ago in a small group of diabetes patients.

But the researchers of the joint US-Brazilian project said yesterday that the transplants appeared to have a lasting effect for the majority of the patients now enrolled in the trial.

The stem cells appear to have “reset” the patients’ immune system not to attack the islet cells that are involved in the production of natural insulin in the body, Dr Burt said.

One patient did not use insulin for four years, four patients remained insulin-free for three years and three patients for two years, and four patients did not use insulin for more than a year after treatment with the stem cells, Dr Burt said.

To find out if the change was lasting the research team measured levels of C-peptides, a marker that shows how well the body is producing insulin. They found levels increased “up to 24 months after transplantation and were maintained until at least 36 months”.

Even in the group that had to restart insulin there was a significant increase in C-peptide levels that lasted at least two years.

“At the present time [it] remains the only treatment capable of reversing type 1 diabetes mellitus in humans,” the team wrote.

A potential drawback is that it is likely to work only within three months of the diagnosis of diabetes in patients, before the immune system has destroyed all the body’s own islet cells.

Iain Frame, director of research at the charity Diabetes UK, said: “Preliminary findings from this small study were reported in 2007. Although this remains an interesting area of research, the importance of a limited extension to this study should not be overstated — this is not a cure for type 1 diabetes.

“As we said in 2007, we would like to see this experiment carried out with a control group for comparison of results and a longer-term follow-up in a greater number of people.”

He added: “It is crucial to find out whether this is associated with the timing of the treatment or possible side-effects of it rather than the stem cell transplant itself.

“It would be wrong to unnecessarily raise the hopes of people living with diabetes about a new treatment for the condition on the back of the evidence provided in this study.”

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