INS and type 2 diabetes mellitus: FMT appears to be a promising approach to reconstruct the gut microbiota in both T1DM (De Groot et al., 2021; Xie et al., 2022) and T2DM patients (Aron-Wisnewsky et al., 2019; Wang et al., 2020; Su et al., 2022) resulting in improved insulin sensitivity, weight loss, reductions in fasting blood glucose and glycated hemoglobin, increased abundance of Bifidobacterium and reduction of pro-infammatory sulfate-reducing bacteria (Bilophila, Desulfovibrio).