Type 1 diabetes (T1D) is the most common metabolic disorder in children. It progresses through three distinct stages, which are now utilized for preclinical diagnosis. Advances in genetics and screening techniques are enhancing the prediction, prevention, and treatment of the disease. The identification of different T1D subtypes has deepened our understanding of the disease's underlying mechanisms, reflecting genetic, clinical, and immunological diversity. Key genetic variations, including high-risk HLA haplotypes such as DR3 and DR4-DQ8, alongside non-HLA variants. Many of these genetic risk regions are also linked to other autoimmune diseases. Early diagnosis enables secondary prevention strategies, notably with teplizumab, the first approved drug for delaying T1D onset, already in use for stage 2 patients in the USA.