Association Between Thyroid-Stimulating Hormone and Diabetic Kidney Disease in Type 2 Diabetes: A Cross-Sectional Study with Mediation Analysis

Objective The relationship between thyroid-stimulating hormone (TSH) and diabetic kidney disease (DKD) in patients with type 2 diabetes mellitus (T2DM) is unclear. This study aimed to clarify the relationship between TSH and DKD and to identify potential mediating factors. Methods A total of 1,390 patients with type 2 diabetes were divided into two groups: a non-diabetic kidney disease (Non-DKD) group and a diabetic kidney disease (DKD) group. We compared the differences in baseline data between the two groups, analyzed the association between TSH and renal function indicators, and categorized TSH levels into normal thyroid function and subclinical hypothyroidism (SCH) using a cutoff of 4.2 mIU/L. Logistic regression was used to compare the DKD prevalence between groups and clarify the TSH-DKD association. A restricted cubic spline model was used to determine if a non-linear relationship exists between TSH and DKD. Subgroup stratification analysis was conducted to examine potential confounding variables' modulation of the TSH-DKD association and their interaction. We also analyze potential mediating factors. Results A comparison of baseline data revealed that TSH levels were significantly higher in the DKD group than in the non-DKD group ( P  < 0.05).TSH was significantly associated with renal function indicators (Cr, GFR-EPI, CysC, and UACR) ( P  < 0.05). TSH showed a positive association with DKD. The probability of developing DKD was 1.56 times higher in subjects with TSH > 4.2 mIU/L (SCH) compared to those with TSH ≤ 4.2 mIU/L(OR: 1.56,95% CI: 1.09–2.23, P  = 0.016). In the restricted cubic spline model, Before adjusting for confounding factors, TSH levels exhibited a significant linear correlation with DKD risk. However, after adjusting for gender, lifestyle, and diabetes-related confounding factors, this association lost statistical significance.There was no interaction between subgroups. TSH indirectly influenced DKD via serum albumin. (β = 0.01, 95% CI: 0.00–0.02, P  = 0.04). Conclusions Among individuals with type 2 diabetes, TSH shows a positive association with DKD, and this relationship might be partially mediated by albumin.