Type 1 Diabetes Mellitus is a complex and polygenic disease due to gene-environment interactions. The role of genetic background of diabetes has been extensively investigated. However, final conclusions have not yet been reached. Family and twin studies have shown that genetic factors are important contributors to the genetic risk of the disease. Although more than 18 diabetes-predisposing genes have been reported to date, only the major histocompatibility complex (HLA) region on chromosome 6p21 (IDDM1) and the insulin gene on chromosome 11p15 (IDDM 2) have been conclusively associated with susceptibility to type 1 diabetes. However, it has been shown recently that cytotoxic lymphocyte antigen 4 (CTLA4) on chromosome 2q33 (IDDM12) and LYP/PTPN22 on chromosome 1p13 also contribute to the genetic risk of T1DM. The article reviews the recent advances in this field. By identifying new loci or reanalyzing the known ones and with the help of more powerful studies, it is possible in the future to be able to shed more light on the complex field of the genetics of type 1 diabetes and to further understand the pathophysiology of the disease, which will allow us eventually to treat or prevent it.