Type 1 diabetes, previously defined as insulin-dependent or juvenile-onset diabetes, is a chronic autoimmune disease characterized by cellular-mediated destruction of the β-cells of the pancreas, leading to absolute insulin deficiency and consequently an aberrant glucose homeostasis. Over the past fifty years a global pandemic of TD1 has been registered and the incidence of the disease in Europe is expected to double in the next decade. The global increase in the disease rate cannot be explained only by genetic alterations or improved diagnostic tools, and thus it was postulated that environmental factors are likely to be involved in this global trend. The intestinal environment, especially its resident flora and its associated immune system have been implicated in the pathogenesis of the disease. The present study aims to characterize the intestinal environment in the most widely used model of the disease, the non-obese diabetic mouse. The gut microbiota, gut permeability and gut immune system will be assessed in four population of mice: three-week old mice, eight-week old mice, mice with recent onset of the disease and long term non progressor mice. This characterization should allow us to understand if any of the variables studied varies in an age dependent manner and is correlated or can predict the onset of the disease in the animal model