This large nationwide study demonstrates a negative association between serum testosterone levels and age among Korean men, with obesity, hyperglycemia, and hypertriglyceridemia as additional contributors to reduced testosterone levels.
Serum testosterone showed a significant linear decline of approximately 0.021 ng/mL per year in Korean men aged 40 and older.
The prevalence of biochemical hypogonadism more than doubled from the youngest to the oldest age group, increasing from 5.5% in men aged 40–49 years to 11.6% in men aged 70 years and older.
Higher BMI, fasting glucose, and triglyceride levels were independently associated with lower testosterone levels in multivariable analysis.
Large-scale population-based testosterone data in Asian men have been limited prior to this study, making regional reference data important for defining testosterone thresholds.
Men with conditions or treatments known to affect androgen metabolism were excluded to reduce confounding in testosterone measurements.
This research suggests that testosterone levels in Korean men decline steadily with age, dropping by about 0.021 ng/mL for every year of age. Using data from nearly 28,000 men who had routine health checkups at 20 hospitals across South Korea, the study found that roughly 1 in 18 men in their 40s had clinically low testosterone, and this proportion roughly doubled to about 1 in 9 men by age 70 or older. This is one of the largest studies of its kind focused on an Asian population, filling a notable gap since most prior research has been conducted in Western countries. Beyond age, the study found that being overweight or obese, having elevated blood sugar (a marker of diabetes risk), and having high triglyceride levels (a type of blood fat) were each independently linked to lower testosterone levels. Interestingly, cholesterol levels (both HDL and LDL) and PSA (a prostate marker) were not significantly associated with testosterone after accounting for other factors. This suggests that metabolic health — particularly body weight and blood sugar control — plays an important role in testosterone levels alongside the natural aging process. This research suggests that regular monitoring of testosterone and metabolic risk factors may be valuable for middle-aged and older men, particularly those who are overweight or have signs of metabolic problems like high blood sugar or triglycerides. The authors call for future longitudinal studies to better understand whether these metabolic factors directly cause testosterone decline or whether the relationship works in the other direction, and to examine the long-term health consequences of low testosterone in Asian men.
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Upload Your LabsTae Hyo Kim, Yu Seob Shin, Zhao Luo, J. Ryu, Jung-Sik Huh, Hyeon Ju Kim, et al.. (2026). Age-Related Testosterone Decline and Metabolic Determinants in 27,687 Korean Men Aged ≥40 Years: A Nationwide Population-Based Study.. The World Journal of Men's Health. https://doi.org/10.5534/wjmh.250369