Patients with Type 1 diabetes who received transplants of insulin-producing cells were able to do without their daily injections for a period of time. However, the beneficial effect eventually wore off for most of the study participants.

The procedure was successful in releasing Type I diabetics from the need for insulin injections -- but only temporarily. The University of Alberta team reported that the beneficial effects disappeared within two years for 86 percent of the patients.

Physicians insert an abdominal tube that drips the transplant cells into the patient's liver, where they become part of tiny blood vessels.

The transplanted cells are obtained from donors, which means that recipients must take immune-suppressing drugs for life to prevent their rejection.

Results of a trial in 2000 were encouraging, but the study only lasted 14 months. The latest research, which involved 36 patients, revealed that many had to go back to insulin injections.

However, those who suffer from the most severe form of the disease may benefit, even though they still need shots, the researchers said. Their findings are published in the New England Journal of Medicine.

They are now investigating possible new drug combinations to enhance the procedure's effectiveness.

Type I diabetes is an autoimmune disorder. The body's own immune system attacks cells in pancreas, destroying them or damaging them to the extent that they stop producing insulin.