A new study that tested stem cell transplants in patients with type 1 diabetes found that many patients were able to live for three years or more without needing insulin.

The study involved 23 patients who had recently been diagnosed with type 1 diabetes and who were injected with stem cells from their own blood. The results showed that 20 were able to live without needing to take insulin, 12 of them continuously and eight briefly.

Of those who remained continuously insulin-free, the time ranged from 14 to 52 months. Of the eight who relapsed, they resumed insulin use at low doses.

The study was led by Dr. Richard K. Burt of Northwestern University's Feinberg School of Medicine and included patients that ranged in age from 13 to 31.

The study offers hope of a way of reversing type 1 diabetes.

"Currently, there are no therapies for type 1 diabetes that keep patients insulin-free ... on no medications at all . . . except this approach," Burt told CTV News.

In healthy people, beta-cells in the pancreas produce insulin, a hormone that helps the body convert glucose into energy.

The beta-cells in a type 1 diabetes patient cannot produce insulin, causing a glucose buildup in the body, which means the patient must take insulin via an injection or a pump for the rest of their lives.

Previous research has found that that a stem-cell transplant, called autologous nonmyeloablative hematopoietic stem cell transplantation (HSCT) helped 15 patients live insulin-free for an average of 19 months.

HSCT involves removing the patient's own blood stem cells, treating them and returning them to the body via intravenous injection.

But there were some serious side-effects noted in the study.

The treatment did not work in three patients, triggered pneumonia in other patients and significantly lowered nine patients' sperm counts.

In previous research, it wasn't clear if the improvements in the patients' health were the result of the treatment and not due to a healthier post-transplant diet and exercise regimen.

Some doctors say this study is interesting but not ready for practical use.

"I would rate it scientifically interesting but not ready for use yet . . . because of the side effects used for this treatment." Dr. Shayne Taback of the Manitoba institute of Child Health told CTV News.

For this study, the researchers measured levels of C-peptide, a byproduct of insulin production, to determine if the beta-cells were indeed functioning better.

They found that among subjects who were able to stay off insulin continuously, C-peptide levels were dramatically higher two years post-transplant, and stayed very high at 36 months.

Even among those who were able to remain insulin-free only briefly, C-peptide levels were considerably higher 36 months after the treatment.

"In conclusion, (HSCT) was able to induce prolonged and significant increases of C-peptide levels associated with absence of or reduction of daily insulin doses in a small group of patients with type 1 (diabetes)," the researchers wrote. "At the present time, (HSCT) remains the only treatment capable of reversing type 1 (diabetes) in humans."

The findings appear in a special diabetes-themed issue of JAMA, the Journal of the American Medical Association.