Diabetes genetic testing is now mostly used for diagnosis of diabetes typing, and it is recommended that genetic testing be performed under the guidance of a physician. Genetic factors play an important role in the development of diabetes mellitus. both T1DM and T2DM are polygenic diabetes mellitus. The heritability (the extent to which genetic factors play a role in the development of the disease) of T1DM was found to be 74%, compared to 44% for T2DM. Among the T1DM susceptibility loci identified to date, HLA-class II genes are the main effectors, especially the human leukocyte antigen-DR (HLA-DR) and human leukocyte antigen-DQ (HLA-DQ) genes. Although HLA susceptibility genotype is not a diagnostic criterion for T1DM, it can reflect the risk of autoimmune morbidity in patients and has an auxiliary diagnostic value. For patients with suspected T1DM and negative pancreatic autoantibodies, HLA susceptibility genotyping can be performed by qualified medical institutions to help diagnosis. Diabetes genetic testing has limited value for the diagnosis and daily management of diabetes. For type 2 diabetes mellitus, the number of patients affected by polygenic factors is much larger than that of monogenic factors, and it is recommended that patients with suspected diabetes mellitus be followed up regularly. When discomfort occurs, seek medical attention promptly.