Statement of the Problem: Nowadays, it is admitted that the transmission of a donor disease through transplantation/transfer of an unhealthy gut microbiota (dysbiosis) fulfills Koch’s postulates on polymicrobial infections. This is the case of disorders such as inflammatory bowel disease, colorectal cancer, obesity, kwashiorkor and environmental enteropathy. This paper provides the literature evidence supporting the idea that T1D, T2D and LADA are a single transmissible polymicrobial infection that can spread both intra- and intergenerationally. Methodology & Theoretical Orientation: Network research focusing on diabetogenic gut microbiota as a crucial environmental factor for the development of all clinical forms of diabetes mellitus. Conclusion & Significance: The transfer of a diabetogenic gut microbiota to genetically susceptible individuals carrying an immature intestinal immune system causes T1D and LADA. In contrast, those with intestinal immune maturation will develop T2D. Ultimately, long-term T2D can compromise gut immunity and progress to T1D.