Correlation analysis between serum free triiodothyronine and C-peptide-based insulin resistance index in euthyroid adults

To explore the correlation between serum free triiodothyronine (FT3) and C-peptide-based insulin resistance index (HOMA2 IR-CP) in euthyroid adults. A cross-sectional study. The clinical data of euthyroid adult participants who underwent physical examination in the Second Medical Center of Chinese PLA General Hospital from January to December in 2019 were retrospectively analyzed. According to the HOMA2 IR-CP level, the participants were divided into HOMA2 IR-CP>2.18 group ( =3 463) and HOMA2 IR-CP≤2.18 group ( =8 204). Univariate Pearson correlation analysis and multivariate logistic regression analysis were used to analyze the correlation between FT3 and HOMA2 IR-CP. The interaction model was used to analyze the interaction between FT3 and related factors, and the dose-response relationship between continuity variable FT3 and HOMA2 IR-CP was explored by using restricted cubic spline plots. A total of 11 667 euthyroid adult participants aged (50.7±10.0)years were recruited according to the inclusion and excl