Type 1 diabetes: stem cell-derived cells that produce insulin

Type 1 diabetes is an autoimmune disease: the body’s own defenses destroy the pancreatic cells that produce insulin (the islets). People who have it depend on insulin injections or pumps for life. One of the most promising lines of research aims to replace those cells using stem cells.

What is the therapy?

The treatment under study, called zimislecel (from Vertex Pharmaceuticals), works like this:

• It starts from pluripotent stem cells, which can become any cell type.
• In the lab they are turned into fully differentiated islets, cells that produce insulin.
• They are given as an infusion into the vein that supplies the liver, where they settle and start producing insulin.
• Patients receive immunosuppressive drugs to prevent rejection.

The results

In June 2025, The New England Journal of Medicine published the phase 1/2 results:

• 12 patients received the full dose and were followed for at least one year.
• 10 of 12 (83%) no longer needed insulin injections.
• All reached an HbA1c below 7% and spent more time with glucose in range.
• None had further episodes of severe hypoglycemia.
• Most adverse events were mild or moderate. There were two deaths that investigators considered unrelated to the therapy.

Who would it be for?

Initially, people with hard-to-control type 1 diabetes who suffer severe hypoglycemia and cannot sense when their blood sugar drops. It could benefit around 60,000 people in the United States and Europe.

Things to keep in mind

• It requires lifelong immunosuppression, with its risks. That is why, for now, it is reserved for the most severe cases.
• The phase 3 study is under way and the company plans to seek approval in 2026.
• Research continues with gene-edited “hypoimmune” cells and encapsulation devices that could avoid immunosuppressants in the future.

For the first time, a treatment with stem cell-derived cells has allowed people with type 1 diabetes to stop using insulin. It is a huge step forward, although it is not yet a cure available to everyone.

This content is for informational purposes only and does not replace evaluation by a health professional. It has not been evaluated by the FDA.