Aims/hypothesis <p>Faecal microbiota transplantation (FMT) may alleviate gastrointestinal symptoms in individuals with diabetic gastroenteropathy, as demonstrated in a recent placebo-controlled trial. In most participants, symptom relief was transient, raising the need for repeated treatments. This study assessed the long-term efficacy, safety and feasibility of repeated, on-demand FMT as a maintenance treatment in this patient population.</p> Methods <p>All 20 participants from the randomised clinical trial were offered extended open-label treatment with FMT. Symptom assessments were conducted by telephone every 2–3 months using the Gastrointestinal Symptom Rating Scale for Irritable Bowel Syndrome (GSRS-IBS). Secondary measures included bowel movement frequency, stool consistency assessed using the Bristol Stool Scale, perceived treatment benefit on a seven-point Likert scale, and adverse events (AEs). FMT was primarily given as oral capsules, and colonoscopy was used for participants who could not swallow capsules.</p> Results <p>Of the original 20 participants, 17 were included in the present study and followed from September 2021 to December 2024, with a median Duration of follow-up of 33.2 months (range 14.7–39.1 months). Participants received a total of 95 FMT treatments, with a median of five per participant and a median interval of 5.3 months between treatments. FMT induced consistent symptom relief, with reduced GSRS-IBS scores across multiple treatments. At the last FMT treatment provided, the mean GSRS-IBS score had decreased from 60 (95% CI 54, 66) at baseline to 35 (95% CI 29, 40), with a mean difference of −25 (95% CI −18, −33). The occurrence of frequent bowel movements 2 weeks after treatment (&gt;&#xa0;7 per day) decreased from 19% (95% CI 10%, 28%) to 3% (95% CI 0%, 7%). Stool consistency improved after treatment, and the frequency of normal stool types (Bristol Stool Scale score 3–5) increased from 28% (95% CI 18%, 39%) to 76% (95% CI 66%, 86%). Participant satisfaction was high, with 86% reporting considerable benefits (Likert scores 5–7). Repeated FMT was generally well tolerated, with most AEs being mild and self-limiting. Fifteen serious AEs were documented, of which only one was deemed to be possibly related to FMT.</p> Conclusions/interpretation <p>Repeated, on-demand FMT is effective and safe for long-term treatment of individuals with type 1 diabetes and severe diabetic gastroenteropathy.</p> Trial registration <p>ClinicalTrials.gov NCT04749030</p> Funding <p>The study was funded by a Steno Collaborative Grant (no. 0058906)</p> Graphical Abstract <p></p>