Abstract: Objective To study the effect of thyroid hormone on insulin resistance in type 2 diabetes patients with subclinical hypothyroidism. Methods A total of 120 patients with type 2 diabetes who were treated in Liaocheng Second People’s Hospital from January 2018 to December 2020 were divided into mild subclinical hypothyroidism group, severe subclinical hypothyroidism group and normal group. All patients were tested for glucose and lipid metabolism and insulin function. The results were compared. The left ventricular function of patients with different TSH levels was compared, and the correlation between TSH and clinical indicators was analyzed. Results Total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C), fasting insulin (FINS), glycosylated hemoglobin (HbA1C), insulin resistance index (HOMA-IR), 2h postprandial blood glucose (2hPG) and thyroid stimulating hormone (TSH) in the severe subclinical hypothyroidism group were higher than those in the subclinical hypothyroidism group and the normal group. Fasting C peptide and islet β cell function index (HOMA-β) were lower than those in the subclinical hypothyroidism group and the normal group. The above indexes in the subclinical hypothyroidism group were different from those in the normal group, and the difference was statistically significant (P<0.05). After treatment, the fasting blood glucose (FPG), TC, TG, LDL-C, FINS, HbA1C, HOMA-IR, 2hPG and TSH in the subclinical hypothyroidism group were lower than those in the severe subclinical hypothyroidism group, and the fasting C peptide and HOMA-β were higher than those in the severe subclinical hypothyroidism group, the differences were statistically significant (P<0.05). The left ventricular ejection fraction (LVEF), left ventricular fractional shortening (LVFS), left ventricular early diastolic mitral valve blood flow velocity / left ventricular end diastolic flow velocity ratio (E/A) in patients with TSH level>10 mIU/L were lower than those in patients with TSH≤10 IU/L, and the differences were statistically significant (P<0.05). TSH level was negatively correlated with fasting C-peptide and HOMA-β, and positively correlated with other indicators above in patients with subclinical hypothyroidism and subclinical hypothyroidism, P<0.05. Conclusion Patients with type 2 diabetes mellitus complicated with subclinical hypothyroidism will have increased insulin resistance and left ventricular dysfunction. Thyroid hormone replacement therapy is helpful to improve the glucose and lipid metabolism disorder and insulin resistance of patients, which can provide reference for the formulation of clinical treatment plan.

Key words: type 2 diabetes, Subclinical hypothyroidism, insulin resistance