Background : Diabetes mellitus (DM) and thyroid dysfunction (TD) are two closely associated disorders. The coexistence of TD could adversely influence metabolic control and even increase the long-term mortality in patients with DM. The objective of the present study was to investigate the prevalence and risk factors of TD in patients with type 2 DM (T2DM). Methods : This is an observational cross-sectional study. A total of 340 patients with newly diagnosed T2DM who were admitted to ward of endocrinology department were included for analysis. Thyroid function was examined and its relationship with demographic, metabolic and diabetes-related parameters were evaluated Results : The prevalence of TD was 21.2% in the total population. The low T3 syndrome was the most frequent TD, in 14.7% of patients. Low FT3 level was associated with diabetic complications including presence of diabetic ketosis (DK) or diabetic ketoacidosis (DKA) (r = -0.388, P ≤ 0.001) and microalbuminuria (r = -0.302, P ≤ 0.001). Metabolic and demographic factors, including age, glycemic control and insulin resistance also correlated with levels of thyroid hormones. DK or DKA (OR = 6.161, P ≤ 0.001) and microalbuminuria (OR = 3.950, P = 0.002) were risk factors of low T3 syndrome. Conclusion : TD is not rarely seen in patients with newly diagnosed T2DM. Diabetic complications and diabetes-related metabolic and demographic factors are related to the presence of TD.