This study aims to evaluate the risk of islet autoimmunity in patients with autoimmune thyroid disease (AITD), describe related clinical and laboratory characteristics, and explore the development of a risk assessment model based on clinical, laboratory, and genetic markers. Adults aged 18-60 years with confirmed AITD will undergo baseline assessment including demographic data, anthropometric measures, lifestyle factors, medical history, thyroid-related clinical information, thyroid function, and thyroid antibody testing. A baseline blood sample will be collected for measurement of islet autoantibodies (GADA, IA-2A, ZnT8A, and IAA). Participants with positive islet autoantibodies will undergo further evaluation of glucose metabolism and beta-cell function, including HbA1c, OGTT, insulin, and C-peptide testing. Genome-wide genetic data will be used to construct a type 1 diabetes-related genetic risk score, and additional HLA genotyping may be performed in autoantibody-positive participants. The study will assess the prevalence and profile of islet autoantibodies in AITD and identify clinical, laboratory, and genetic factors associated with islet autoantibody positivity.