Background: Diabetes mellitus and thyroid dysfunction are two common endocrine disorders. The unrecognized subclinical Thyroid dysfunction may adversely affect metabolic control and increase cardiovascular risk. Our aim was to investigate the prevalence and patterns of Thyroid dysfunction in patients with type 2 diabetes mellitus in an observational cross-sectional study. Screening for thyroid dysfunction in diabetic patients will allow early treatment of hypothyroidism. Thyroid hormones and insulin both are involved in cellular metabolism antagonistically. Therefore, excess or deficit of any one of them may result in metabolic derangement. Recently, interest has been raised for the influence of thyroid hormone action on insulin levels. Conflicting data are available on influence of insulin levels on thyroid dysfunction. The development of IR may also lead to many metabolic abnormalities. Objective: Study of thyroid dysfunction in type 2 diabetes mellitus. Methods: Data was collected from the Type 2 Diabetes mellitus patients who visited the OPD or got admitted at KR Hospital, Mysore medical college, Mysore. The necessary blood tests, urine examination and imaging were done as per the proforma. Results: In our study,16 out 100 patients had abnormal thyroid profile.7 patients have overt hypothyroidism,5 patients have subclinical hypothyroidism,3 have hyperthyroidism and 1 has subclinical hyperthyroidism. Our study has high Prevalence of Thyroid dysfunction in females among type 2 diabetes mellitus. Conclusion: This study showed high prevalence of thyroid dysfunctions in patients of type 2 diabetes mellitus. Hence, we conclude that screening for thyroid dysfunction among patients with diabetes mellitus should be routinely performed, so as to recognize these dysfunctions early