Stem Cell-Derived Islet Cells Show Promise in Early Trial for Severe Low Blood Sugar

Zimislecel is an investigational treatment being developed by Vertex Pharmaceuticals. Unlike traditional insulin therapy, it uses stem cells that have been grown in the laboratory and fully transformed into islet cells—the insulin-producing cells normally found in the pancreas. The goal is to restore the body's natural ability to regulate blood sugar by infusing these cells into the liver.

Data from the Phase 1/2 FORWARD clinical trial, presented in June 2025 and published in the New England Journal of Medicine, tracked 12 participants with Type 1 diabetes who experienced severe low blood sugar events. All 12 who received a full dose of zimislecel as a single infusion achieved the American Diabetes Association's recommended blood sugar targets within one year.

Using continuous glucose monitoring to track blood sugar patterns, researchers found that participants averaged 93% time-in-range—meaning their blood sugar stayed in the healthy target zone (70–180 mg/dL) for nearly all of the day. This exceeds the guideline target of 70% time-in-range.

Remarkably, 10 of the 12 participants were able to stop taking insulin injections entirely after receiving zimislecel.

Most side effects reported were mild or moderate in severity. There were no serious adverse events directly linked to zimislecel itself. Two deaths occurred during the study period, but both were unrelated to the treatment and had been previously reported.

The overall safety profile was consistent with what researchers expected from the immunosuppressive medications participants took and the islet infusion procedure itself. Participants receiving islet transplants require immunosuppressive drugs to prevent the body from rejecting the infused cells, and those medications carry their own considerations that doctors weigh carefully.

These results represent an important step in exploring whether stem cell-derived islet cells can help people with Type 1 diabetes regain more natural blood sugar control. For people experiencing severe low blood sugar events—which can be dangerous and frightening—a therapy that reduces or eliminates insulin dependence could meaningfully improve quality of life.

However, this is still very early-stage research with a small number of participants and relatively short follow-up time. Key questions remain: How long do the benefits last? What happens to the infused cells over years or decades? And how will the treatment work in larger, more diverse groups? Zimislecel is not yet approved by regulatory agencies and remains an investigational therapy. Anyone interested in learning more should speak with their diabetes care team.

Origin: diabetestimes.co.uk (News report). Evidence: News report — unverified, pending corroboration. Type1Cure is an information and intelligence hub, not a medical advice service. This article summarizes published research and does not provide diagnosis, treatment, or personal medical guidance. Always talk to your own care team before changing anything about your Type 1 diabetes management.