Autoimmunity has been implicated to be the major cause of thyroid–dysfunction associated diabetes mellitus. Thyroid disorders remain the most frequent autoimmune disorders associated with type 1 diabetes mellitus (T1DM) and are known to be highly prevalent in all forms of the diabetes including with type 2 diabetes mellitus (T2DM). The present study is planned to establish the relationship between the Autoimmune Thyroid Disorders and type 2 diabetes mellitus. It was a hospital based cross sectional observational study carried out in Department of Medicine, Silchar Medical College and Hospital, Silchar, Assam. Total 120 patients of type 2 are selected from OPD and IPD in a random fashion. All the patients were evaluated for thyroid dysfunction and autoimmune anti thyroid antibodies. Abnormal thyroid dysfunction was found in a large number of diabetic patients (28.33%). Subclinical hypothyroidism, overt hypothyroidism and primary hyperthyroidism were observed in 16.7%, 8.3% and 3.3% of diabetic patients respectively. A high titer of anti–thyroid antibodys and autoimmune thyroid disorders were also found in many T2DM subjects which were statically significant. The study show an increased prevalence of autoimmune thyroid disorders in patients with type 2 diabetes mellitus