Background– There is a complex interrelationship in the co–existence of thyroid dysfunction among diabetic patients and may be related to the growth of cardiovascular diseases and other complications of long–term metabolic imbalances. The prevalence of thyroid dysfunction varies from 10 to 24% among diabetic patients. Objective– To determine the prevalence of thyroid dysfunction among the patients with diabetes mellitus in a tertiary care hospital at Kalaburagi, India. Methods– This retrospective study was conducted during June 2018 analysing the records of diabetes patients attending to the diabetes OPD, Department of General Medicine in the past one year and their association with thyroid dysfunction was studied. Results– A total number of 200 diabetes mellitus Type I and Type II patients were included in the study. Out of 200patients, 27 (22.5 %) had thyroid dysfunction and remaining 93 patients had normal thyroid function. Out of 27 thyroid dysfunction patients, 8 (6.6%) had clinical hypothyroidism, 17 (14.1%) had subclinical hypothyroidism and 2 (1.6%) diabetics had hyperthyroidism. Conclusions: Thyroid is common among type 2 diabetic patients, especially in females. It is most commonly secondary to autoimmune thyroid disease. Microvascular complications are commonly observed in this group of patients with dual endocrinal disorder treating physicians should routinely screen thyroid in patients with diabetes mellitus to prevent complications.