To investigate the correlation between subclinical hypothyroidism (SCH) and diabetic kidney disease (DKD), renal function injury in patients with type 2 diabetes mellitus (T2DM).

A total of 656 patients with T2DM in the Metabolic Disease Hospital of Tianjin Medical University were enrolled from September 2017 to August 2018 and divided into non-DKD group (425 cases) and DKD group (231 cases) according to whether they merged DKD or not. The level of thyroid stimulating hormone(TSH) and the prevalence of SCH and so on were compared between two groups. All patients were divided into three groups according to their TSH levels: TSH normal low value group(TSH<2.5 mIU/L,n=383), TSH normal high value group(2.5 mIU/L≤TSH≤4.2 mIU/L, n=199) and SCH group(TSH>4.2 mIU/L,n=74). The prevalence of macroalbuminuria and DKD, injury markers of renal function and other indicators were compared among the three groups. The correlation between different levels of TSH and DKD was investigated by logistic regression analysis.

Compared with non-DKD group, the level of thyroid stimulating hormone(TSH) and the prevalence of SCH were increased(Z=3.670, χ²=12.978, all P<0.05) in DKD group. Compared with TSH normal low value group and TSH normal high value group, the proportion of female, prevalence of macroalbuminuria, prevalence of DKD and the level of 24-hour urinary protein were increased, whereas the estimated glomerular filtration rate (eGFR) and FT₄ level were decreased in SCH group (F=10.713-305.951, all P<0.05). No significant differences were found between TSH normal low value group and TSH normal high value group (allP>0.05) for all of those indicators.Logistic regression analysis showed that SCH was independently correlated with DKD (OR=2.187, 95% CI: 1.244-3.847, P<0.05).

SCH is significantly correlated with DKD and renal function injury in patients with T2DM.

Subclinical hypothyroidism; Diabetic kidney disease; Type 2 diabetes mellitus