Vertex's Islet Cell Therapy Shows Dramatic Reduction in Dangerous Low Blood Sugar Levels in Type 1 Diabetes Trial

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Vertex's islet cell therapy, zimislecel (formerly VX-880), significantly reduced dangerously low blood sugar events (severe hypoglycemia) in a phase 1/2 trial for patients with Type 1 diabetes and impaired hypoglycemic awareness235.

All 12 study participants who received the full zimislecel infusion engrafted the stem-cell-derived islets, began producing glucose-responsive endogenous C-peptide, and showed restored endogenous insulin secretion for at least one year235.

After 90 days, none of the patients experienced any severe hypoglycemic events; by 12 months, 10 of the 12 no longer needed exogenous insulin therapy, marking a 92% mean reduction in daily insulin use2345.

Participants achieved recommended glycemic control targets, with HbA1c levels below 7% and greater than 70% time in range, meeting the study's primary endpoints235.

Adverse events related to zimislecel were consistent with expected outcomes for islet infusion and immunosuppressive regimens, with no new safety concerns reported3.

The positive results were presented at the American Diabetes Association's annual conference in June 2025 and published in the New England Journal of Medicine35.

Sources:

2. https://www.fiercebiotech.com/biotech/vertexs-remaining-islet-cell-therapy-reduces-dangerously-low-blood-sugar-levels-phase-12

3. https://www.cgtlive.com/view/vertex-islet-cell-therapy-vx-880-restores-endogenous-insulin-secretion-type-1-diabetes

4. https://www.biospace.com/drug-development/vertexs-cell-therapy-could-be-functional-cure-for-diabetes-but-market-prospects-uncertain

5. https://www.statnews.com/2025/06/20/stem-cell-therapy-type1-diabetes-study/