Abstract:Objective To investigate the incidence of low triiodothyronine (T₃) syndrome in type 2 diabetes mellitus (T2DM) and its correlation with the development of diabetic nephropathy (DN). Methods A total of 185 patients with T2DM hospitalized in Central Hospital of Bengbu from January 2020 to February 2022 were retrospectively selected and divided into three groups according to urinary albumin to creatinine ratio (ACR) : normoalbuminuria group (group A ,n=84, ACR＜30 mg/g), microalbuminuria group (group B, n=54, 30 mg/g≤ACR＜300 mg/g) and macroalbuminuria group (group C,n=47, ACR≥300 mg/g). Venous blood lipid, glycosylated hemoglobin (HbA1c), and liver, kidney and thyroid function levels were measured to analyze the correlation between thyroid function and ACR. The estimated glomerular rate filtration (eGFR) was calculated by serum creatinine according to the CKD-EPI formula. The diagnosis of low T₃ syndrome was confirmed by combining the inverse T₃(rT₃) level, Results With the increase of ACR level (group A → group B → group C), plasma T₃ and free T₃ (FT₃) levels were gradually decreased (F=9.019, 18.702, P＜0.01), and the incidence of low T₃ syndrome was gradually increased in group A (0), group B (3.70%) and group C (14.89%) (χ²=14.666, P＜0.01). There were statistically significant differences in age, smoking history, diabetes course, systolic blood pressure, albumin, blood urea nitrogen, eGFR, FT₃ and T₃ among the three groups (P＜0.05). Multiple linear regression analysis showed that FT₃ was negatively correlated with ACR (β=-0.330, P＜0.05), systolic blood pressure was positively correlated with ACR (β=0.203, P＜0.05). Conclusion The occurrence of low T₃ syndrome in T2DM patients is related to ACR level. Early detection of thyroid hormone level is helpful for the early diagnosis and disease evaluation of T2DM patients with DN.