Every day, roughly 537 million people around the world manage some form of diabetes. For those with type 1 diabetes, an estimated 9 million adults and more than 1.2 million children and adolescents globally, management is not optional, not adjustable, and never finished. It means multiple insulin injections every single day, constant blood sugar monitoring, and a permanent awareness that the body is missing something it can never make on its own. The cells that produce insulin have been destroyed, and until now, science has had no reliable way to replace them. That may be about to change.
Researchers at Karolinska Institutet and KTH Royal Institute of Technology in Sweden have developed what they describe as a significantly improved method for growing insulin-producing cells from human stem cells. Published in April 2026 in the peer-reviewed journal Stem Cell Reports, the findings show that these lab-grown cells can regulate blood sugar effectively in laboratory tests and, crucially, reverse diabetes in mice. For the millions of people living with type 1 diabetes and the researchers who have spent decades searching for a biological fix, it is one of the most encouraging results in years.
What Type 1 Diabetes Actually Does to the Body
To understand why this research matters, it helps to understand what type 1 diabetes takes away.
The pancreas contains clusters of cells called islets of Langerhans. Inside those islets are beta cells, the only cells in the human body capable of producing insulin, the hormone that allows glucose to enter cells and fuel the body. In type 1 diabetes, the immune system misidentifies these beta cells as foreign invaders and destroys them. Once they are gone, the body loses the ability to regulate blood sugar on its own, permanently.
The consequence is a life defined by external management. Once symptoms are present, multiple daily insulin injections are required, titrated to frequently measured blood or interstitial fluid glucose levels. There is no day off, no plateau where the body stabilizes, and no currently available treatment that addresses the root cause rather than its consequences. Insulin keeps people alive, but it does not cure the disease.
The Problem With Previous Stem Cell Approaches
The idea of replacing destroyed beta cells with lab-grown versions is not new. Scientists have been exploring it for decades, and the logic is straightforward: if stem cells can be coaxed into becoming any type of cell in the body, why not the specific cell type 1 diabetes destroys?
The challenge has always been in the execution. Previous methods of producing beta cells from stem cells have consistently run into the same problem. When cells were allowed to self-organize into three-dimensional clusters, the natural structure of pancreatic islets, the results were inconsistent. Some cell lines performed well. Others produced cells that looked right under a microscope but failed to function properly when exposed to glucose. The variability made scaling any treatment approach nearly impossible.
The Swedish team tackled this problem directly. Led by Professor Per-Olof Berggren from the Department of Molecular Medicine and Surgery and Professor Fredrik Lanner from the Department of Cell and Molecular Biology, the researchers developed a new protocol that guides stem cells through a more controlled maturation process. Instead of allowing the cells to organize themselves freely, the method imposes a more structured developmental pathway, one that produces consistently high-quality insulin-producing cells across multiple different human stem cell lines.
“We have developed a method that reliably produces high-quality insulin-producing cells from multiple human stem cell lines,” said Professor Berggren. The implication of the word “reliably” is significant. Reliability is precisely what previous approaches lacked, and it is the foundation on which any scalable therapy must be built.
The full details of the research are available through the published findings in Stem Cell Reports from Karolinska Institutet, and represent one of the most methodologically rigorous approaches to beta cell regeneration published to date.
What the Results Actually Show
The lab results from the new protocol were striking across two key measures.
First, the cells responded strongly to glucose. This matters enormously because a beta cell that produces insulin at a fixed rate regardless of blood sugar levels is nearly as dangerous as no beta cell at all. The body needs insulin to rise when blood sugar is high and fall when it is low. The Swedish team’s lab-grown cells demonstrated this dynamic responsiveness, the fundamental behavior that makes a beta cell useful rather than merely present.
Second, when transplanted into diabetic mice, the cells reversed the disease. Blood sugar levels, which had been dangerously elevated due to the absence of functional beta cells, returned to normal after the transplant. The mice’s bodies responded to the lab-grown cells as if they were performing the role that their own immune systems had destroyed.
These lab-grown cells not only respond strongly to glucose but are also able to restore blood sugar control when transplanted into diabetic mice. The team now plans to move toward clinical trials to treat type 1 diabetes in humans, a step that, if successful, would represent the most significant development in diabetes treatment since the discovery of insulin itself more than a century ago.
This research sits within a broader wave of regenerative medicine breakthroughs that are beginning to approach problems medicine has long considered intractable, a pattern explored in how gene therapy is transforming treatment for inherited diseases once considered permanent.
The Immune Rejection Problem
Every discussion of beta cell replacement therapy eventually arrives at the same obstacle: the immune system.
In type 1 diabetes, the immune system has already demonstrated its willingness to attack and destroy insulin-producing cells. Transplanting new ones, even perfectly functional lab-grown cells, does not automatically solve this problem. Without additional intervention, the same immune response that destroyed the original beta cells could destroy the transplanted ones, too.
Current approaches to this challenge generally involve immunosuppressive drugs that dampen the immune response broadly enough to protect the transplanted cells. But immunosuppression carries its own risks, including increased vulnerability to infection and, over time, damage to other organs. It is a significant trade-off that limits which patients are considered suitable candidates for transplantation.
The Swedish team’s new protocol addresses one dimension of this problem. Professor Berggren noted that the ability to produce high-quality cells from multiple human stem cell lines “opens up opportunities for future patient-specific cell therapies, which could reduce immune rejection.” Patient-specific therapy using a patient’s own cells, genetically modified and then matured into beta cells, would theoretically eliminate immune rejection, since the transplanted cells would not be recognized as foreign.
This approach is still in development, but it points toward a version of the therapy where immunosuppression might not be required at all. That would transform the risk profile of the treatment and dramatically expand the population of patients who could benefit from it.
Where the Field Stands More Broadly
The Karolinska research does not stand alone. It arrives as several parallel approaches to beta cell replacement are advancing simultaneously, each attacking the immune rejection and cell quality problems from different angles.
Vertex Pharmaceuticals has developed insulin-producing cells grown from stem cells, which led to the first sustained insulin production in a group of 12 people with type 1 diabetes. Their therapy, known as zimislecel, uses stem-cell-derived insulin-producing cells infused into the liver, where they sense glucose and produce insulin. Like current transplant approaches, it still requires immunosuppressive drugs, but it represents the first time stem-cell-derived beta cells have produced sustained insulin in actual human patients. Vertex plans to submit the therapy to the FDA in 2026.
Separately, a clinical milestone reached in early 2025 showed that transplanted islet cells engineered to evade the immune system could produce insulin in a human patient without any immunosuppression at all for more than 60 weeks. Full details on this landmark result are available through the clinical research published by Breakthrough T1D, and they point toward the same destination the Karolinska team is pursuing: a treatment where the immune system is no longer an obstacle.
Together, these developments suggest that beta cell replacement therapy for type 1 diabetes is no longer a distant theoretical possibility. It is a clinical reality in early form, being refined across multiple institutions simultaneously.
What the Research Does Not Yet Prove
Honesty about the limitations of this research matters, particularly for the millions of people with type 1 diabetes who have watched promising developments fail to translate into treatments for decades.
The Karolinska study has been conducted in laboratory conditions and in mice. The gap between reversing diabetes in a mouse model and developing a safe, effective, scalable treatment for human patients is substantial. Mice are not people; their immune systems differ from human immune systems in important ways, and many therapies that perform well in animal models encounter unexpected complications in human trials.
The immune rejection problem, while partially addressed by the patient-specific therapy concept, has not yet been fully solved. Clinical trials will need to determine not just whether the cells function correctly in humans, but also how to protect them from immune attack without creating unacceptable risks from immunosuppression.
According to the World Health Organization’s diabetes data, type 1 diabetes currently has no known prevention and no cure, a classification that will not change until large-scale human trials demonstrate long-term safety and efficacy. The path from a promising animal study to an approved treatment typically takes a decade or more.
The Cost and Access Dimension
Even if clinical trials succeed, the question of who can access the resulting treatment will be critical. Advanced cell therapies are among the most expensive medical interventions ever developed. The first approved gene therapies carry price tags in the millions of dollars per treatment, figures that place them entirely out of reach for patients in most of the world.
Type 1 diabetes is a global condition, but access to insulin itself remains unequal. Most of the deaths occurring in children and youth with type 1 diabetes are due to non-diagnosis, with the young person dying in ketoacidosis, misdiagnosed as another condition, or not reaching care. A treatment that replaces existing daily insulin dependency with a one-time cell therapy would need to be dramatically more affordable than current gene therapy pricing to reach the populations that need it most.
This tension between scientific possibility and economic accessibility runs through nearly every major medical breakthrough of the past decade and connects to the broader forces reshaping how global healthcare systems allocate resources under pressure.
Looking Ahead
The announcement from Karolinska Institutet is not the end of the story, but it may be one of its most important turning points. For decades, the standard answer to “Will there ever be a cure for type 1 diabetes?” has been “We are working on it.” That answer has not changed, but the credibility behind it has.
Multiple institutions are now converging on the same biological target using different but compatible approaches. The cell quality problem is being solved. The immune rejection problem is being tackled from several angles at once. The first human patients have already received stem-cell-derived insulin-producing cells and produced insulin as a result.
The team at Karolinska plans to move toward clinical trials. If those trials confirm what the lab and animal results suggest, the implications extend far beyond type 1 diabetes alone. A reliable method for producing functional insulin-producing cells from human stem cells would advance the broader field of regenerative medicine, potentially opening paths to similar approaches for other conditions where specific cell types are lost or damaged.
For the 9 million adults and 1.2 million children living with type 1 diabetes today, waking up every morning to a condition that demands constant vigilance and offers no respite, that is not a small thing. It is the possibility, still distant but now more tangible than it has ever been, that the cells their bodies destroyed might one day be grown back.
This article is for informational purposes only and does not constitute medical advice. Patients with type 1 diabetes should consult their endocrinologist or healthcare provider regarding treatment options.
