A new study published in The New England Journal of Medicine found that an experimental stem cell therapy allowed most participants with type 1 diabetes to stop using insulin entirely.
The treatment, known as zimislecel, involves allogeneic stem cell–derived islet cells—engineered cells designed to mimic the body’s natural insulin-producing function. Researchers from institutions including the University of Toronto, University of Wisconsin, University of Chicago, City of Hope National Medical Center, USC, Boston Children’s Hospital, and others conducted the study.
A total of 14 participants received the therapy and were followed for at least 12 months. All had type 1 diabetes and undetectable C-peptide levels at baseline, indicating no natural insulin production. After receiving zimislecel through a portal vein infusion, every participant showed signs of engraftment and new islet cell function based on the reappearance of C-peptide.
Among the 12 participants who received a full dose, all avoided severe hypoglycemic events and achieved a hemoglobin A1C level below 7%. Ten of the 12—roughly 83%—were fully insulin-independent by day 365, meaning they no longer required exogenous insulin injections.
While the findings are promising, there were safety concerns. Neutropenia was the most frequent serious side effect, and two participants died—one from cryptococcal meningitis and another from complications of preexisting neurocognitive issues.
The researchers describe this as an interim analysis and stress the need for additional trials to confirm long-term safety and effectiveness. Still, the results offer compelling early evidence that stem cell-derived islet therapies like zimislecel may one day provide a functional cure for some people living with type 1 diabetes.
