Roc curve analysis of GTT, ALT, AST and ALT/AST in diabetes vs. control group was as follows: AUC = 0.685; (95% CI: 0.673–0.694; p < .0001; Cut‐off value: >21.36; Sensitivity: 70.25%; Specificity: 57.76%), AUC = 0.564; (95% CI: 0.553–0.575; p < .0001; Cut‐off value: >14; Sensitivity: 70.85%; Specificity: 39.88%), AUC = 0.588; (95% CI: 0.577–0.600; p < .0001; Cut‐off value: <14; Sensitivity: 43.33%; Specificity: 71.64%), AUC = 0.669; (95% CI: 0.658–0.679; p < .0001; Cut‐off value: >1.06; Sensitivity: 68.87%; Specificity: 57.29%), respectively. This evidence concerns the gene GPT and diabetes mellitus.