GPT and type 2 diabetes mellitus: Univariate linear regression showed an association between SAF and age (R = 0.479, P <  0.001), sex (R = − 0.070, P = 0.045), smoking (R = 0.140, P <  0.001), drinking (R = 0.151, P <  0.001), T2DM duration (R = 0.260, P <  0.001), hypertension (R = 0.134, P <  0.001), and fatty liver (R = 0.103, P = 0.021) as well as the levels of 2-h PBG (R = 0.141, P = 0.007), 2-h C-peptide (R = − 0.140, P = 0.007), TGs (R = − 0.136, P <  0.001), ALT (R = − 0.143, P <  0.001), BCr (R = 0.387, P <  0.001), BUA (R = 0,178, P <  0.001), Cys-C (R = 0.243, P <  0.001), and eGFR (R = − 0.301, P <  0.001).