High triglyceride–glucose index and changes in triglyceride–glucose index are associated with an increased risk of hypogonadism in middle-aged Taiwanese men: a retrospective longitudinal study

Purpose: The triglyceride-glucose (TyG) index is a well-established marker of metabolic and cardiovascular risk. Although prior research has identified inverse associations between the TyG index and androgen-related health-including testosterone levels and erectile dysfunction-there is limited data on how longitudinal changes in this index correlate with hormonal shifts. Therefore, this study investigated the association between dynamic changes in the TyG index and total/free testosterone levels within a retrospective Taiwanese cohort to evaluate its utility in identifying men at risk for androgen deficiency. Materials and methods: Data were obtained from a longitudinal MJ Health Screening Center database in Taiwan (2011-2022), comprising repeated health examination records of 4,269 men aged 45-65 years. Collected variables included demographic characteristics, triglyceride, fasting sugar, TyG index, and total testosterone. To account for within-subject correlations in the repeated measurements, generalized estimating equations (GEEs) were employed using multivariate models to analyze the associations between TG/FG phenotypes, TyG index, and hypogonadism. Results: Among 4,269 men aged 45-65 years (7,268 records), 11.2% had hypogonadism. After adjustment for measurement time, age, body mass index, waist circumference, blood pressure, and high-density lipoprotein, the TyG index was significantly associated with increased hypogonadism risk (odds ratio [OR] = 1.90; 95% confidence interval [CI], 1.58-2.28; p < 0.001) and inversely with free testosterone (β = -0.294, p = 0.005). Compared with the normal fasting glucose and normal triglycerides (NFGNT) group, the Hypertriglyceridemic fasting glycemia (HTFG) group exhibited the highest risk (OR = 2.55) and the greatest reduction in free testosterone (β = -0.530), followed by the high triglyceride (HTG) group (OR = 2.16; β = -0.465) and the elevated fasting glucose (EFG) group (OR = 1.61; β = -0.254). In men with baseline testosterone ≥300 ng/dL, hypogonadism risk increased up to 2.38-fold when the TyG index increased by ≥0.5." Conclusions: In conclusion, the TyG index serves as a valuable tool for identifying men at risk of androgen deficiency. Longitudinal increases in this index are independently associated with an elevated risk of hypogonadism and declining free testosterone levels, with the high triglyceride with high fasting glucose (HTFG) group exhibiting the most pronounced risk.