In what researchers are calling a potential breakthrough in diabetes treatment, a new stem cell-based drug has effectively cured 10 out of 12 people suffering from severe type 1 diabetes. After a single infusion of the experimental therapy, called zimislecel, most of the participants no longer needed insulin injections – a life-altering shift for those living with the most dangerous form of the disease.
This treatment, developed by Vertex Pharmaceuticals, was designed specifically for patients with hypoglycemic unawareness, a condition where blood sugar crashes happen without warning and can result in fainting, seizures, coma, or even death.
Who Led the Study and What Did It Involve?
The trial was conducted by researchers at the University Health Network in Toronto, led by Dr. Trevor Reichman, a pancreas and islet transplant specialist. The findings were presented at the American Diabetes Association meeting and published in The New England Journal of Medicine in June 2025.
The study recruited 14 participants, all of whom had type 1 diabetes complicated by hypoglycemic unawareness. In this condition, the body no longer gives signs when blood sugar is dangerously low, making it especially difficult to manage.
Participants were given an infusion of lab-grown islet cells – tiny clusters that naturally produce insulin. These cells were created from stem cells and delivered through a vein into the liver, where they took hold and began functioning like natural insulin-producing cells. The participants also had to take immunosuppressant drugs to prevent their bodies from rejecting the new cells.
The Results: 83 Percent Cured
Of the 12 participants who completed the trial, 10 – about 83 percent – were insulin-free after one year. The other two dramatically reduced their insulin use. Blood sugar control significantly improved, with average time spent in a healthy glucose range jumping from 50 percent at the start to over 93 percent after a year.
Even more remarkable: the dangerous episodes of low blood sugar completely disappeared in all trial participants.
“This is a game-changer,” said Dr. Christoph Buettner of Rutgers Medical School. “It enables patients to receive enough insulin from these new islets and, hence, will cure them.”
Dr. Reichman added, “This is the first time a single infusion of lab-grown cells has safely replaced natural insulin production in patients with type 1 diabetes.”
Side Effects and Limitations
Though the results are promising, the treatment is not without risks. All participants must continue taking immunosuppressive drugs indefinitely. These medications weaken the immune system and can increase the risk of infections and certain types of cancer.
In the trial, two participants died—one from a fungal brain infection and another from complications related to pre-existing dementia. Both deaths were determined to be unrelated to the drug itself. The most common side effects were gastrointestinal issues, headaches, and nausea.
Traditional islet cell transplants require organ donations, usually needing two or three donors per recipient. The timing depends on donor availability, and long-term insulin independence is rare. This new approach provides a standardized, scalable solution using lab-grown cells, eliminating the reliance on donors.
In past isolated cases, people have gone off insulin after islet transplants, but this is the first time such success has been replicated in a controlled trial using stem cell-derived cells.
When Could This Be Available?
Zimislecel is now moving into larger phase 3 trials, with researchers monitoring participants for a full ten years. The company plans to apply for FDA approval within five years, though the final cost of the treatment has not yet been disclosed.
Efforts are also underway to develop an updated version of the therapy that wouldn’t require immunosuppressive drugs. One such version, called XV-264, failed in early testing, but new approaches like genetic editing and protective cell enclosures are still in development.
Amanda Smith, 36, one of the trial participants, told The New York Times that she felt like she was “living a whole new life” after going off insulin just six months post-treatment. Another patient, Marlaina Goedel, who was diagnosed at age five, called her doctor a “superhero” after her blood sugar normalized within a month of her infusion.
Goedel said she used to worry daily if she’d wake up the next morning. Now cured, she’s back to horseback riding and planning for college, no longer tied to needles and glucose monitors.
Roughly 1.6 million Americans live with type 1 diabetes, and about 30 percent have the dangerous subtype treated in this study. While zimislecel won’t be available to the general public for a few more years, this trial signals a powerful step toward a future where diabetes may no longer be a life sentence.
“Managing insulin is not easy,” said Dr. Kathleen Wyne of Ohio State. “Even with modern pumps and sensors, it’s still an exhausting job. This new treatment could free people from that burden.”
Although challenges remain, the momentum behind this therapy offers real hope that the world is getting closer to curing one of the most relentless chronic diseases.
