Objectives: We aimed to explore the correlation between thyroid function and diabetic kidney disease (DKD) in patients with type 2 diabetes mellitus (T2DM). Methods: A total of 7516 T2DM patients were enrolled and grouped according to DKD status. Clinical parameters, including blood glucose parameters, thyroid function, and indicators of renal impairment, were collected and compared between the DKD and Non-DKD groups. Correlation analysis and univariate/multivariate logistic regression analyses were performed. Results: Age, T2DM duration, the use of insulin and lipid-lowering drugs, systolic and diastolic blood pressure, body mass index, and fasting blood glucose levels were greater in the DKD group than in the Non-DKD group (p p p Conclusions: Thyroid hormone levels, especially FT4 levels, were significantly negatively correlated with DKD in T2DM patients.