Host–microbiome interactions in human type 2 diabetes following prebiotic fibre (galacto-oligosaccharide) intake

Randomized placebo-controlled study in men aged 42-65 years with well-controlled type 2 diabetes receiving stable treatment, many of whom were taking metformin. For the prebiotic group, 14 participants were randomized and analyzed; the placebo group included 15 participants.

Participants in the active arm received 5.5 g/day of a galacto-oligosaccharide prebiotic mixture (Bi 2 muno) taken orally in sachets, mixed into beverages or food, for 12 weeks. The comparator was maltodextrin placebo.

Prebiotic supplementation did not improve glucose control, gut barrier function, endotoxaemia, inflammation, or overall gut microbiota composition versus placebo. Key glucose outcomes were not significant, including fasting glucose (P=0.227), glucose tAUC 180 min (P=0.485), glucose iAUC 180 min (P=0.221), fasting insulin (P=0.543), and insulin tAUC 180 min (P=0.112). No adverse side effects were reported. The authors concluded there was no evidence for a role of prebiotics in treating type 2 diabetes in this cohort, although some microbiome associations were noted and were not robust after multiple testing.

The active arm was small, with only 14 randomized/analyzed participants, and the intervention lasted just 12 weeks. Findings are limited to men with well-controlled type 2 diabetes, many of whom were treated with metformin and had relatively high baseline fibre intake, which may have reduced the chance of detecting an effect. Some reported microbiome associations did not remain robust after multiple testing, raising the possibility of chance findings.