Association of triglyceride-glucose index with serum testosterone and semen parameters in fertile and infertile men

Aim: The triglyceride-glucose (TyG) index serves as a practical surrogate measure of insulin resistance (IR), a condition known to exert adverse effects on male reproductive function. This investigation examined how the TyG index relates to serum testosterone concentrations and sperm quality indicators in men with and without fertility impairment.

Materials and Methods: This retrospective study enrolled 302 men who were stratified by their TyG index into two groups: low (TyG < 8.1, n = 78) and high (TyG > 8.1, n = 224). Participants were additionally classified according to fertility status. Reproductive hormones, semen characteristics, and metabolic variables were compared. Statistical evaluation employed Spearman rank correlation and multiple linear regression adjusted for age, body mass index (BMI), and varicocele presence. Receiver operating characteristic (ROC) curve analysis was performed for infertility status and biochemical hypogonadism.

Results: The High-TyG group was significantly older and had higher BMI, fasting glucose, total cholesterol, triglycerides, and low-density lipoprotein cholesterol, alongside lower total testosterone and high-density lipoprotein cholesterol, than the Low-TyG group (all p < .001). Lower testosterone in the High-TyG group was observed among primary and secondary infertile men, but not among fertile men. The TyG index showed significant inverse correlations with total testosterone (ρ = -0.354, p < .001) and non-progressive motility (ρ = -0.338, p < .001). Multivariable regression identified the TyG index as a significant independent predictor of total testosterone (B = -56.26, 95% confidence interval [CI]: -87.52 to -25.00, p < .001). The area under the ROC curve (AUC) was 0.892 (95% CI: 0.855 – 0.928) for infertility status and 0.692 (95% CI: 0.619 – 0.765) for biochemical hypogonadism.

Conclusion: Elevated TyG index co-exists with metabolic disturbances, diminished testosterone, and impaired sperm motility. Given its derivation from standard laboratory measurements, the TyG index may offer a cost-efficient means to flag subfertility risk.