Autologous fecal microbiota capsules are safe and potentially preserve beta-cell function in individuals with type 1 diabetes.

This study investigated the safety and feasibility of daily ingestion of autologous lyophilized fecal microbiota capsules (a-LFMCs) for preserving beta-cell function in individuals with type 1 diabetes (T1D). We evaluated a-LFMC in an open-label, single-arm pilot study (NCT05323162) with 10 individuals with T1D. The study included a 3-month run-in period, 3 months of daily a-LFMC treatment, and a 3-month follow-up. Beta-cell function was assessed using mixed-meal stimulated C-peptide area under the curve (AUC). During the run-in period, beta-cell function significantly declined (mean ΔAUC -12.02 ± 5.09 nmol/L*min, p = 0.025). There was no decrease in beta-cell function during the a-LFMC treatment period (mean ΔAUC 0.76 ± 5.09 nmol/L*min, p = 0.88) and the follow-up period (mean ΔAUC 0.96 ± 5.09 nmol/L*min, p = 0.85). No serious adverse events occurred, though constipation increased during the treatment period (0% vs. 30%, p = 0.021). a-LFMC treatment was found to be safe and potentially contributes to preserving beta-cell function in T1D patients. A larger randomized placebo-controlled trial is needed to confirm these promising findings.