Microbiome Capsules to Stabilize Beta-Cell Function in T1D
Pleun de Groen, Coco M. Fuhri Snethlage, Koen Wortelboer, Sevilay Tokgöz, Mark Davids, Xanthe Verdoes, Florine H.M. Westerbeke, Rick I. Meijer, Martin Gotthardt, Willem M. de Vos, Hilde Herrema, Max Nieuwdorp, Nordin M.J. Hanssen
Autologous fecal microbiota capsules are safe and potentially preserve beta-cell function in individuals with type 1 diabetes Gut Microbes. 2025 Dec 31;17(1):2563155.
Type 1 diabetes (T1D) is characterised by progressive destruction of pancreatic beta cells. Preservation of residual beta-cell function is associated with better glycaemic control, lower insulin requirements, and reduced risk of hypoglycaemia and long-term complications. sGrowing evidence implicates the gut microbiome in T1D pathogenesis and progression. Alterations in microbial composition have been observed across disease stages, and experimental models suggest that microbiome–immune interactions in the small intestine may influence autoimmune responses against beta cells. A previous randomized trial showed that autologous fecal microbiota transplantation (FMT) delivered via a duodenal tube could preserve beta-cell function in recent-onset T1D, but this invasive approach limits feasibility for long-term use. This study evaluated whether daily oral ingestion of autologous lyophilized fecal microbiota capsules (a-LFMCs) is a safe, practical, and potentially effective way to preserve beta-cell function in people with early T1D.
This was an open-label, single-arm pilot study including 10 adults with T1D diagnosed 0.5–3.5 years earlier. Participants completed a 3-month run-in period to assess natural beta-cell decline, followed by 3 months of daily a-LFMC ingestion and a 3-month follow-up. Beta-cell function was assessed using mixed-meal stimulated C-peptide area under the curve (AUC). Safety, gastrointestinal symptoms, microbiome composition, and duodenal gene expression were also evaluated.
Key findings:
- Beta-cell function declined significantly during the run-in period but did not decline during the a-LFMC treatment or follow-up period.
- No serious adverse events occurred, and overall compliance with daily capsule ingestion was high.
- Gastrointestinal symptoms such as abdominal pain, reflux, indigestion, and diarrhea did not increase during treatment.
- Constipation increased during the treatment period but resolved after discontinuation of a-LFMCs.
- Fecal microbiota composition shifted toward the capsule microbiota after treatment, suggesting partial microbial engraftment.
- Duodenal biopsies showed increased expression of genes related to immune modulation and epithelial barrier function after treatment.
- No significant changes were observed in systemic plasma cytokine concentrations, indicating primarily local intestinal effects.
This pilot study suggests that daily ingestion of autologous fecal microbiota capsules is safe, feasible, and well tolerated in adults with early T1D. The stabilization of C-peptide decline following treatment, compared with the clear deterioration during the run-in period, provides preliminary evidence that microbiome-based interventions may help preserve residual beta-cell function beyond the immediate post-diagnosis phase.
Although the single-arm design precludes causal inference, the findings support further investigation of capsule-based autologous FMT as a practical, non-invasive adjunctive therapy in T1D. Larger randomized controlled trials will be needed to confirm efficacy, determine optimal dosing strategies, and clarify the underlying immune-microbial mechanisms.
Concluding, the authors state
"a-LFMCs appear to be a safe and potentially promising approach for performing daily FMTs in individuals with type 1 diabetes" -
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