Potential role of maintaining physiological testosterone levels in improving glucose metabolism among normal-weight Japanese women: a pilot exploratory study.

BACKGROUND

Traditionally, elevated androgen levels in women have been associated with obesity and deteriorated glucose metabolism. However, most existing data are derived from patients with polycystic ovary syndrome (PCOS) or obesity. Consequently, the physiological role of maintaining testosterone levels in normal-weight women remains poorly understood.

OBJECTIVE

To eliminate metabolic biases associated with obesity, this exploratory study investigated the relationship between serum total testosterone levels and parameters of body fat and glucose metabolism (HbA1c, fasting plasma glucose, and HOMA-IR) specifically in normal-weight Japanese women (BMI 18.5-25 kg/m²).

METHODS

Out of 100 Japanese women who underwent health checkups, 69 normal-weight individuals were included in the analysis. Correlations between total testosterone levels and glucose metabolism indices were examined.

RESULTS

Total testosterone levels showed significant inverse correlations with HbA1c (ρ = -0.341, p = 0.004), fasting glucose (ρ = -0.327, p = 0.006), and HOMA-IR (ρ = -0.274, p = 0.023). In multivariate regression analysis, these inverse associations remained significant for HbA1c and fasting glucose after adjusting for BMI and lifestyle factors. Conversely, while the associations with HbA1c and fasting glucose were attenuated after adjusting for age and menopausal status, the inverse association between total testosterone and HOMA-IR remained independently significant after adjusting for age (β = -0.178, p = 0.029) and further for menopausal status (β = -0.173, p = 0.032).

CONCLUSION

This study demonstrates that even in normal-weight women, low total testosterone levels are associated with impaired glucose metabolism. These results suggest that, in the absence of obesity-induced androgen excess, the maintenance of physiological androgen levels may contribute to metabolic maintenance in women. These findings suggest a novel perspective on female metabolic health, highlighting the potential importance of physiological androgen homeostasis in the regulation of glucose metabolism.