Background: Diabetes mellitus has become a major health problem worldwide. Through Various Studies it has been have found that diabetes and thyroid disorders mutually influence each other and both disorders tend to coexist. The aim of this was study was to find out the prevalence of thyroid dysfunction in patients with type 2 diabetes mellitus attending an outpatient department and medical wards of hamdard institute of medical sciences and research institute new Delhi. Material and methods: The study was conducted on 300 patients of type 2 diabetes mellitus above 30 years of age. All the patients were evaluated for thyroid dysfunction by testing thyroid profile (T3, T4and TSH). The correlation of prevalence of thyroid dysfunction with gender distribution, age distribution, HbA1C was done. The observations and interpretations were recorded and results obtained were statistically analysed. Results: It was found that prevalence of thyroid dysfunction was 17. 3% in diabetic patients, most common was subclinical hypothyroidism (9%). Thyroid dysfunction was found to be more in females 73. 1 %, as compared to males 26. 9%. There was significant association between prevalence of thyroid dysfunction with HbA1c. Conclusion: On the basis of observations of this study it is recommended to routinely screen patients of diabetes for presence of thyroid disorders to prevent long term morbidity and mortality.