With respect to the pancreas, type 1 diabetes mellitus is an autoimmune disease associated with
progressive beta cell destruction and subsequent insulin dependence in the first 2–3 decades of life
(prevalence 19 per 100,000, more males than females age of onset 5–25 years), which is associated
with an increased morbidity and mortality risk [23]. Altered intestinal microbiota composition and
increased intestinal permeability have been shown to be present in DM1 patients [24,25]. In this re-
gard, recent mouse studies suggest that interaction in the small intestinal lamina propria between the
intestinal microbes and the innate immune system (most likely T-helper cell type 17 (Th17) is a critical
epigenetic factor in the development of type 1 diabetes mellitus [26]. Indeed, a very recent paper by
Korsgren links the increased incidence of T1D during the last decades to differences in the intestinal
bacterial flora [27]. These data also suggest that bacteria entering the pancreatic ductal system could
trigger
b-cell destruction and thus induce type 1 diabetes mellitus. During this process, tolerance to
gastrointestinal commensals is lost and microbiota-specific T cells are activated that affect beta cell
function [28]. Based on these findings, we have recently initiated a randomized controlled double
blinded trial using fecal transplantation to investigate the effect on beta cell insulin secretion capacity
in subjects with recently diagnosed type 1 diabetes mellitus. This work is in line with our previous
work in insulin resistant (type 2 diabetes mellitus) subjects who are also characterized by increased
intestinal permeability [29] and altered intestinal microbiota composition [30]. In a double blind
randomized controlled trial in 18 treatment-naive insulin resistant male subjects, we were the first to
show that fecal transplantation induced changes in specific (small) intestinal butyrate producing
bacteria were associated with (temporarily) improved insulin sensitivity [31].