Could Stem Cell Therapy Finally Cure Type 1 Diabetes?

Researchers may have just taken a groundbreaking step toward ending insulin injections for Type 1 diabetics. A new study published in the New England Journal of Medicine shows that stem cell-derived pancreatic islets helped 10 out of 12 participants become insulin-independent after just one infusion. This could be a game-changer in how we treat—and possibly cure—Type 1 diabetes.

Key Takeaways

A total of 14 participants received Zimislecel; 12 of them were given the full therapeutic dose. The findings were remarkable:

• Zero severe hypoglycemic events occurred during the main evaluation period.
• 10 of 12 full-dose participants were insulin-independent at 12 months.
• All participants had restored insulin production, confirmed by C-peptide detection.
• A1C levels dropped by an average of 1.81 percentage points.
• Glucose time-in-range rose to over 93% by day 365.

How Zimislecel Works

Engineered Islet Cells for Insulin Regulation

Zimislecel consists of fully differentiated, allogeneic pancreatic islet cells created from pluripotent stem cells. These cells are infused into the portal vein and begin producing insulin in response to blood glucose levels—essentially mimicking the natural behavior of pancreatic beta cells.

C-Peptide: A Measure of Endogenous Insulin

C-peptide levels were undetectable in all participants at baseline. After zimislecel infusion, all participants showed measurable C-peptide during fasting and stimulated conditions, indicating successful engraftment and function of the transplanted cells.

Full-Dose Results and Visual Data

Twelve participants received a full dose of zimislecel. Here’s what happened:

• No severe hypoglycemic events occurred between days 90 and 365.
• All participants reached an A1C < 7% by day 120 and sustained it through day 365.
• All showed restored insulin production (C-peptide detectable in all cases).

Insulin Production and Glucose Tolerance

This shows continuous improvement in endogenous insulin function.

• At day 90, the average C-peptide level was 424 pmol/L.
• At day 180: 1036 pmol/L; at day 270: 1104 pmol/L; at day 365: 1274 pmol/L.

Panel A shows the mean C-peptide levels (lower limit of detection, 13 pmol per liter) (left) and mean glucose levels (right) over time during a 4-hour mixed-meal tolerance test at baseline and at day 90 and day 180 after zimislecel infusion. Panel B shows the mean fasting C-peptide level and mean mixed-meal–stimulated C-peptide level at 90 minutes (left) and the mean fasting glucose level and mean mixed-meal–stimulated glucose level at 90 minutes (right) at baseline and at day 90, day 180, day 270, and day 365 after zimislecel infusion. Data are shown for the 12 participants who received the full dose of zimislecel (0.8×10⁹ cells) as a single infusion and completed at least 12 months of follow-up. Fasting C-peptide and glucose levels were calculated as the mean of the level at 10 minutes before the mixed-meal tolerance test and the level at the start of the test. 𝙸 bars indicate 95% confidence intervals.

A1C Improvements

• Baseline A1C: 7.8% (range 7.1–9.9)
• By day 120, all participants had A1C < 7% (range 5.7–6.7)
• Mean A1C reduction: 1.81 percentage points by day 365

Reduced Insulin Use

• Mean insulin dose dropped 92% from baseline to day 365.
• 10 participants became completely insulin-independent.
• 2 participants reduced their dose by 70% and 36% respectively, both due to high-dose glucocorticoid exposure (prohibited by protocol).

Panel A shows the glycated hemoglobin level over time. Blue lines indicate the glycated hemoglobin level in individual participants, the solid black line indicates the mean glycated hemoglobin during visits with data obtained from at least 5 participants, and the dashed line indicates the upper limit of the glycated hemoglobin level recommended by the American Diabetes Association (ADA) and European Association for the Study of Diabetes (EASD). Panel B shows total daily insulin dose over time. Blue lines indicate the total daily insulin dose in individual participants, and the solid black line indicates the mean total daily insulin dose during visits with data obtained from at least 5 participants. Data are shown for the 12 participants who received the full dose of zimislecel as a single infusion and completed at least 12 months of follow-up. 𝙸 bars indicate 95% confidence intervals.

Glucose Time-in-Range

• Baseline: mean time in range was 49.5%
• By day 150: All participants exceeded 70% time in range
• Day 365: mean time in range was 93.3% (range 79.5–96.9)
• Glucose variability improved from 36.3% to 20.0% by day 365

Panel A shows the percentage of time in which the glucose level was in the target range of 70 to 180 mg per deciliter (3.9 to 10 mmol per liter) recommended by the ADA and EASD during the follow-up period. Blue lines indicate the percentage of time that individual participants spent in the target glucose range, the solid black line indicates the mean time in the target range during visits with data obtained from at least 5 participants, and the dashed line indicates the lower limit of the percentage of time in the target range recommended by the ADA and EASD for persons with type 1 diabetes. Panel B shows the mean distribution of the percentage of time spent below, within, and above the target glucose range. Percentages may not sum to 100 because of rounding. Data are shown for the 12 participants who received the full dose of zimislecel as a single infusion and completed at least 12 months of follow-up. 𝙸 bars indicate 95% confidence intervals.

Risks and Considerations

Managing Immunosuppressive Therapy

Participants were given glucocorticoid-free immunosuppressants to prevent rejection. Most adverse events were mild to moderate. However:

• Neutropenia occurred in 3 participants.
• Transient liver enzyme elevations and reduced renal function were observed, likely linked to immunosuppressive drugs.

Participant Deaths: Context Matters

Two deaths occurred but were unrelated to zimislecel:

Participant	Cause of Death	Related to Therapy?
1	Cryptococcal meningitis post-surgery	No
2	Progressive dementia from prior injury	No

These were attributed to underlying conditions or protocol deviations, not zimislecel itself.

What This Means for People With Diabetes

Beyond Daily Injections

Restoring islet function with one infusion is a monumental shift from lifelong insulin therapy. For most trial participants, this meant:

• No more daily injections
• Reduced glucose variability
• Elimination of severe lows

When Could This Be Available?

The therapy is still in early-phase clinical trials. Broader access depends on:

• Completion of phase 3 trials
• Long-term safety monitoring
• FDA and global regulatory approvals

The Path Forward

Scaling for Mass Availability

Unlike insulin vials, zimislecel involves live-cell therapy. Production will need to scale massively to meet demand. Manufacturing and quality control for biologics are significantly more complex.

What Needs to Happen Next

To reach patients, zimislecel must clear these hurdles:

• Larger, diverse clinical trials
• Robust tracking of long-term outcomes
• Streamlined FDA review process

Public investment and regulatory streamlining could accelerate access.

Conclusion: A New Hope for the Diabetes Community

• All participants restored insulin production.
• 83% of full-dose participants became insulin-independent.
• Glucose control and A1C improved to near-normal levels.
• Deaths were unrelated, and adverse events were manageable.
• This therapy could eliminate insulin dependence for millions.

The study’s results show that a one-time stem cell therapy may one day replace daily insulin injections, offering a future with fewer complications, fewer needles—and far more freedom.

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