Type 1 diabetes (T1D) is caused by using the autoimmune destruction of insulin producing beta-cells. Multiple genes are regarded to modulate susceptibility to the improvement of T1D. However, clinical studies of T1D have proven a notably low concordance rate in equal twins, suggesting a strong environmental thing in the development of the disease. While the specific triggers of T1D are no longer properly established, many environmental factors such as infections, diet, intestine microbiome and vitamin D deficiency have been suggested to be involved. Interestingly, the incidence of T1D has been growing in parallel with the childhood weight problems epidemic, suggesting that high calorie diet or obesity may be environmental triggers for the increasing incidence of T1D.