Could Stem-Cell Islets Cure Type 1 Diabetes? A 2025 Trial

Type 1 diabetes is, at its heart, a problem of missing cells: the immune system destroys the islet cells in the pancreas that make insulin, leaving people dependent on insulin injections for life. So the dream has always been simple to state and very hard to achieve — replace those cells. A 2025 trial took a real step toward it, growing insulin-making islets from stem cells and giving them to patients, with results good enough to make headlines ¹. It's a genuine milestone. It also comes with an important catch that the headlines often skip.

Reading this well means holding two truths at once: this is exciting, legitimate science — and it is not yet the universal cure it can sound like.

What question did the researchers ask?

The researchers asked whether islet cells grown from stem cells could be infused into people with type 1 diabetes and actually take over the job of producing insulin — safely, and well enough to reduce or remove the need for injected insulin ¹.

The therapy, called zimislecel, is made by coaxing stem cells to become fully differentiated islet cells — real, functioning insulin-producing cells, not a drug. These are infused into the liver's blood supply, where they can settle and respond to blood sugar the way a healthy pancreas would. If the idea of turning stem cells into specific tissues is new to you, our stem-cell overview explains how that works.

What did the trial find?

This was a small, early phase 1–2 trial, and within those limits the results were genuinely impressive. Of the 12 patients who received a full dose, 10 (about 83%) no longer needed any insulin injections a year after treatment. And all 12 met key targets: no severe hypoglycaemic (dangerous low blood sugar) events, an HbA1c below 7%, and more than 70% of the time in the healthy blood-sugar range ¹.

For anyone who lives with type 1 diabetes, those numbers are remarkable. Restoring the body's own glucose-responsive insulin control — rather than chasing it with injections — is exactly the goal, and this is one of the strongest human signals yet that it's achievable.

How strong is this evidence — and what's the catch?

The result is real, but two things keep it honest. First, this was small and short: 12 patients, one year. We don't yet know how long the cells keep working, how they perform across thousands of patients, or what the long-term safety looks like.

Second — and this is the catch that matters most — the cells come from a donor stem-cell source, so the immune system sees them as foreign. To stop rejection, patients must take lifelong immune-suppressing drugs, just like an organ-transplant recipient. That's a serious trade-off: immunosuppression carries its own risks (infections and others), so this approach makes most sense for people whose type 1 diabetes is already dangerous and hard to control — not, yet, for everyone with the condition. The holy grail researchers are still chasing is islet cells that don't require immunosuppression; this trial isn't that, but it proves the cells themselves can work.

What could this mean if you are considering treatment?

For now, the honest message is hope with realism. Stem-cell islet therapy is not a widely available treatment — it's an investigational therapy studied at specialist centres, and the immunosuppression requirement means it's currently aimed at selected, high-risk patients. It is not something to seek from a clinic offering "stem cells for diabetes", which is a very different and unproven proposition.

If you live with type 1 diabetes, this trial is a genuine reason for optimism about the direction of the field. The useful questions for a specialist are about trials and eligibility, and about whether the trade-offs of immunosuppression make sense for your situation. In the meantime, the proven foundations — careful glucose management, modern insulin tools and regular monitoring like HbA1c — remain the basis of care.

What we see at the clinic

People sometimes ask us whether "stem cells can cure diabetes", often having seen a hopeful headline. We try to be precise and honest: legitimate stem-cell islet research like this is genuinely exciting and advancing, but it's early, specialist, trial-based, and tied to immunosuppression — and it is worlds apart from unregulated "stem cell" infusions marketed as diabetes cures, which we'd steer anyone away from. Telling the two apart is exactly where careful guidance helps.

Common questions

Does this cure type 1 diabetes? It freed 10 of 12 patients from insulin for at least a year ¹ — a functional cure for them, short-term. But it's a small trial and requires lifelong immunosuppression, so it's a milestone, not a finished universal cure.

Why do patients still need immune-suppressing drugs? Because the islet cells come from a donor stem-cell source, the immune system would otherwise reject them. Avoiding that need is the next big research goal.

Can I get this treatment now? Not as standard care. It's investigational, offered through specialist trials, and currently suited to selected high-risk patients — not a service from general "stem cell" clinics.

[1] Stem Cell–Derived, Fully Differentiated Islets for Type 1 Diabetes (zimislecel; FORWARD trial). New England Journal of Medicine. 2025. https://doi.org/10.1056/NEJMoa2506549

Key takeaway

In a 2025 trial, islet cells grown from stem cells freed 10 of 12 people with type 1 diabetes from insulin injections for a year, with excellent blood-sugar control — one of the strongest signals yet that lab-grown islets can restore the body's own insulin. The catch is real: it needs lifelong immunosuppression and was small and short, so it's a genuine milestone and a reason for hope, not a ready, universal cure.