Abstract
The gut microbiota is increasingly recognized as an important factor in the pathogenesis of type 1 diabetes (T1D), although its exact role in disease initiation and progression remains uncertain. Earlier interpretations considered alterations in intestinal microbial composition as secondary effects of immune dysregulation or metabolic disturbance. Recent longitudinal studies, however, suggest that specific microbial changes occur before the onset of islet autoimmunity, indicating a potential contributory role in the early phases of disease development. In this narrative review article, the gut–pancreas axis (GPA) is described as a dynamic and reciprocal system in which microbial, metabolic, and immune processes influence each other to shape β-cell outcomes. Evidence from human cohorts and experimental models links early life reductions in microbial diversity, impaired intestinal barrier function, and decreased production of short-chain fatty acids (SCFAs) to altered immune activation and β-cell damage. Microbiota transferred from individuals at risk for T1D has been shown to accelerate disease in animal models, supporting a possible causal relationship. Although experimental models support mechanistic links between microbiota alterations and autoimmune diabetes, current human evidence remains largely associative. Together, these findings suggest that microbial and immune networks interact in a feedback manner that can sustain immune tolerance or promote autoimmunity depending on environmental and host factors. Understanding T1D as a state of disrupted microbial and immune integration provides a basis for restoring gut–pancreas communication and preserving β-cell integrity.