Are We Getting Closer to a Functional Cure for Type 1 Diabetes?
More than a century after the discovery of insulin transformed type 1 diabetes (T1D) from a rapidly fatal disease into a manageable chronic condition, treatment may be entering another transformative period.
An estimated 9.5 million people were living with T1D worldwide in 2025, a 13% increase from 8.4 million in 2021. Approximately 513,000 new cases were estimated in 2025 alone, while the global T1D population is projected to reach 14.7 million by 2040.
Continuous glucose monitors, insulin pumps and automated insulin delivery have dramatically improved disease management. Yet these technologies share one fundamental limitation: they compensate for the biological function that T1D destroys rather than restore it.
That distinction may finally be beginning to change.
Over the past two years, several clinical programs have demonstrated that insulin-producing cells can be restored in people with T1D. Some patients have achieved complete insulin independence. Genetically engineered islets have survived without systemic immunosuppression. At the same time, disease-modifying immunotherapy is moving earlier into the course of T1D to preserve beta-cell function before it disappears.
Together, these advances raise a question that would have seemed far more speculative only a few years ago: Are we getting closer to a functional cure for type 1 diabetes?
What Would a Functional Cure Actually Mean?
T1D occurs when the immune system destroys insulin-producing beta cells. A functional cure would restore sufficient insulin production to maintain glycemic control without regular insulin therapy, even if the underlying autoimmunity is not completely eliminated.
Achieving this requires three things:
- Replace lost beta cells,
- Protect them from immune destruction,
- Preserve their function long term.
Recent clinical advances suggest progress on all three fronts.
Stem-Cell-Derived Islets Can Restore Insulin Production
Vertex’s zimislecel (formerly VX-880) is a stem-cell-derived islet therapy designed to restore insulin production without relying on scarce donor tissue.
Why it matters
In the Phase 1/2 study, all 12 full-dose participants achieved HbA1c below 7% and remained free from severe hypoglycemic events after Day 90. Most importantly, 10 of 12 (83%) were insulin-independent at one year, providing strong evidence that stem-cell-derived islets can restore meaningful insulin production in humans.
The limitation
Patients still require chronic immunosuppression to prevent rejection. The study also reported serious adverse events, including two deaths that investigators did not attribute directly to zimislecel. This currently limits the therapy’s potential for the broader T1D population.
What comes next
After a temporary manufacturing-related dosing delay, Vertex resumed treatment in 2026.
In parallel, Vertex is developing a separate next-generation therapy, VX-017. Like zimislecel, it uses stem-cell-derived islet cells, but VX-017 is designed to broaden treatment eligibility regardless of a patient’s blood type. VX-017 has not yet been tested in humans: the FDA recently cleared it to enter clinical development, and Vertex plans to begin a Phase 1/2 trial.
Can New Beta Cells Survive Without Immunosuppression?
Sana Biotechnology is testing a different strategy: genetically engineering islet cells to evade immune recognition, potentially eliminating the need for chronic immunosuppression.
Why It Matters
In a first-in-human study, UP421 hypoimmune donor islets were transplanted into a patient with T1D without systemic immunosuppression. At 14 months, the cells remained functional and continued to produce insulin, with no evidence of immune rejection.
This provides early human evidence that engineered islets may survive and function without systemic immunosuppression, one of the biggest barriers to broader cell replacement therapy.
The Limitation
The evidence comes from a single patient, and the treatment did not achieve insulin independence. UP421 uses donor islets, so limited donor-cell supply also remains a barrier.
What Comes Next
Sana is developing a separate next-generation therapy, SC451, which combines its immune-evasion technology with stem-cell-derived islets. Unlike UP421, this approach could provide a scalable source of replacement cells while potentially avoiding chronic immunosuppression.
If successful, SC451 could address two major barriers at once: cell supply and immune rejection.
12 Patients, 12 Cases of Insulin Independence
Another strategy is to improve the immunosuppression used with conventional donor-islet transplantation. At the University of Chicago Medicine, investigators are evaluating tegoprubart, an investigational anti-CD40L antibody from Eledon Pharmaceuticals.
Why It Matters
In June 2026, investigators reported that all 12 participants had achieved insulin independence. Their most recent mean HbA1c was approximately 5.4%, compared with around 8.0% before transplantation, and none had experienced severe hypoglycemia following treatment. Median follow-up was eight months, with the longest reaching 22 months.
The Limitation
The study includes only 12 adults, with relatively short follow-up. Tegoprubart also improves the immunosuppression strategy rather than eliminating it, while dependence on deceased-donor islets makes large-scale treatment difficult.
What Comes Next
The University of Chicago study is expanding to additional patients. Eledon has also submitted an IND for a company-sponsored registrational study of tegoprubart in islet transplantation.
Making Islets from a Patient’s Own Cells
Researchers in China are testing another approach: producing replacement islets from a patient’s own cells.
Why It Matters
In a first-in-human Phase 1 study, a woman with T1D received chemically induced pluripotent stem-cell-derived islets (CiPSC islets) generated from her own cells.
She achieved insulin independence 75 days after transplantation. Her time in the target glucose range increased from 43.18% to 96.21% by Month 4, subsequently exceeding 98%, while HbA1c stabilized at approximately 5%.
The Limitation
This is an early result from a single patient. Using a patient’s own cells may reduce immune incompatibility, but it does not necessarily prevent the underlying T1D autoimmune process from attacking the replacement cells. Personalized cell manufacturing could also be difficult and expensive to scale.
What Comes Next
The Phase 1 study is ongoing, with additional patients enrolled. Researchers will now need to confirm whether the insulin independence observed in the first patient can be reproduced and maintained in a larger group.
What If We Preserve Beta Cells Before Replacing Them?
While cell therapies attempt to replace beta cells already lost, teplizumab (Tzield) takes a different approach: preserving the insulin-producing cells a patient still has.
Why It Matters
Teplizumab is an anti-CD3 monoclonal antibody that targets the autoimmune process underlying T1D. In 2026, its use expanded significantly. In April, the FDA expanded the Stage 2 indication to adults and children one year of age and older, allowing earlier intervention to delay progression to Stage 3 T1D.
Then, in June, the FDA granted accelerated approval for children aged 8 to 17 with recently diagnosed Stage 3 T1D, based on evidence that teplizumab slowed the decline of endogenous insulin production measured by C-peptide.
The Limitation
Teplizumab does not restore beta cells already lost and does not eliminate the need for insulin. Its role is to preserve endogenous insulin production and slow disease progression.
What Comes Next
The 2026 expansion into both younger Stage 2 patients and recently diagnosed Stage 3 patients broadens the potential role of teplizumab across the T1D disease continuum. Longer-term studies will determine how durable beta-cell preservation is and whether it translates into meaningful long-term clinical benefits.
So, Have We Found a Functional Cure?
Not yet, but for the first time, we can see what it may look like.
Different clinical programs have now demonstrated key pieces of the solution in humans:
- Preserve: Protect the beta cells that still remain and slow their loss.
- Replace: Restore insulin production by replacing beta cells that have already been destroyed.
- Protect: Shield transplanted cells from immune attack so they can survive and function long term.
No single therapy has yet achieved all three. But with each component now being tested in patients, a functional cure is moving from a theoretical possibility toward a realistic clinical goal.
Advancing the Next Generation of Diabetes Clinical Research
As type 1 diabetes research moves beyond disease management toward potentially transformative therapies, clinical development is becoming increasingly complex. Cell-based treatments, immune-modulating therapies, and novel approaches to beta-cell preservation require carefully designed studies, specialized clinical expertise, and effective patient recruitment strategies.
At Cromos Pharma, we support sponsors in navigating these challenges through tailored clinical trial solutions, operational expertise, and patient-centered approaches. Our goal is to help accelerate the development of innovative therapies and bring promising treatments closer to the patients who need them.
Developing a novel therapy? Contact our team at inquiry@cromospharma.com to discuss how we can support your clinical development program.
