Causal relationship between gut microbiota and diabetic complications: a two-sample Mendelian randomization study.

Background: Imbalances in gut microbiota (GM) have been proposed as a potential contributing factor to diabetic complications; however, the causal relationship remains incompletely understood.

Methods: Summary statistics were obtained from genome-wide association studies (GWAS) of 196 gut microbial taxa, including 9 phyla, 16 classes, 20 orders, 32 families, and 119 genera. These data were then analyzed using mediation Mendelian randomization (MR) analyses to explore the potential mediating effect of diabetes complications risk factors on the relationship between gut microbiota and specific diabetic complications such as diabetic kidney disease (DKD), ketoacidosis, and diabetic retinopathy (DR).

Results: In our Mendelian analysis, we observed negative associations between Bifidobacterial order and Actinomycete phylum with DKD in type 1 diabetes (T1D) as well as early DKD in T1D. Conversely, these taxa showed positive associations with ketoacidosis in type 2 diabetes (T2D). In reverse Mendelian analysis, we found that DR in both T1D and T2D as well as ketoacidosis in T2D affected the abundance of Eubacterium fissicaten genus and LachnospiraceaeUCG010 family within the gut microbiota.

Conclusions: Our findings provide compelling evidence for causal relationships between specific GM taxa and various diabetes complications. These insights contribute valuable knowledge for developing treatments targeting diabetes-related complications.