Autoimmune diabetes mellitus is characterized by selective destruction of beta pancreatic cells and by cellular infiltration with T- (particularly Th1) and B-lymphocytes. The marker of autoimmunity is the presence of autoantibodies (ICA, IAA, GADab, IA2ab). Etiology of the autoimmune process is still unknown. It is suggested that the pathogenesis is activated by genetic and environmental factors. Individual predisposition can influence also the onset and progression of the disease. The most important genetic risk factors of autoimmune diabetes mellitus are the HLA class II alleles (DQB10302, 0201; DRB10301, 0401; DQA1*0301, 0501) and the risk alleles of INS-VNTR of the promoter region. Recent studies have shown various genetic risk factors for the autoimmune diabetes mellitus. Individual predispositions belong to the genetic polymorphisms in cytokine genes (IL-10, IL-12, IL-18) and the microsatellite polymorphism of MHC class I chain-related gene A (MIC-A).