Triiodothyronine and Free Thyroxine Levels Combined with Thyroid-Stimulating Hormone Are Associated with Glucose Metabolism in Obese Patients with Euthyroid Function

Purpose: To present thyroid hormones (THs) cutoff values to assess the association of THs and glucose metabolism in obese patients with euthyroid function. Methods: This study investigated 445 obese patients (235 females and 210 males) with euthyroid function received treatment in the department of endocrinology of shanghai 10th people’s hospital from 2011 to 2019, with the median age of 29 years (interquartile range 22-35 years). The cut-offs for thyroid-stimulating hormone (TSH), free triiodothyronine (FT3) and free thyroxine (FT4) were 2mIU/L, 16mIU/L, and 5mIU/L, respectively. Results: Fasting blood glucose (FBG) and 2h-glucose (BG120) were significantly higher in low FT3 (P<0.05) and high FT4 patients (P<0.05). In patients with TSH under 2mIU/L, a low FT3 group was robustly associated with higher FBG and BG120 levels (P<0.05). In patients with TSH under 1.5mIU/L, additional association with lower fasting and 2h-insulin (P<0.05) could be found. FT3 had no predictive value in high TSH patients. In patients TSH over 1.5 or 2mIU/L, a high FT4 group was robustly associated with higher FBG and BG120 levels (P<0.05). FT4 had no predictive value in low TSH patients. Patients with TSH over 2mIU/L, high FT4 group had a crude odds ratio of 2.65(95% Confidence interval 1.40-5.03, P=0.003) for FBG compared with low FT4 and remained significant after adjustments for age, gender and body mass index. Similar results could be obtained in patients with TSH over 1.5mIU/L. Conclusions: A combination of TSH and FT4/FT3 instead of only one thyroid hormone indicator had predictive value of glucose metabolism in obese patients with euthyroid function. Disclosure J. Zhang: None. G. Li: None. X. Cheng: None. X. Wang: None. M. Jayachandran: None. Y. Huang: None. S. Qu: None. Funding National Key Research and Development Program of China (2018YFC1314100); National Natural Science Foundation of China (81970677); Shanghai Pujiang Program (2019PJD040); Effect of ApoC3 High Expression on Islet Cells and Related Molecular Mechanism (03.05.18.002)