Association of the glycolipid index GLM7 with polycystic ovary syndrome: an exploratory mediation analysis of serum total testosterone

Polycystic ovary syndrome (PCOS) is characterized by complex and interrelated metabolic and endocrine disturbances. However, whether the novel glyco-lipid seven-factor index (GLM7) is associated with greater odds of PCOS remains unclear, and the potential mechanisms underlying this association have not been fully elucidated. A total of 1,149 infertile women were included in this retrospective case-control study, including 162 women with PCOS and 987 women without PCOS. Multivariable logistic regression and restricted cubic spline (RCS) analyses were performed to examine the association between GLM7 and the odds of PCOS. An exploratory mediation analysis was conducted to evaluate the statistical contribution of serum total testosterone (TT) to the observed association between GLM7 and PCOS. Propensity score matching (PSM) based on age and body mass index (BMI) was performed as a sensitivity analysis. The Akaike information criterion (AIC) was used to compare the relative model fit of GLM7 with that of conventional individual metabolic markers. GLM7 were significantly higher among women with PCOS than among those without PCOS. In the multivariable logistic regression analysis, each one-unit higher GLM7 was associated with greater odds of PCOS after covariate adjustment (adjusted OR = 1.95, 95% CI: 1.38–2.74, P < 0.001). Among the models evaluated, the model including GLM7 had the lowest AIC value (AIC = 828.91), indicating comparatively better model fit. RCS analysis showed a significant overall association between GLM7 and the odds of PCOS, with no evidence of nonlinearity. In the propensity score–matched cohort, which included 157 women with PCOS and 321 women without PCOS, higher GLM7 remained significantly associated with greater odds of PCOS in the unadjusted model (OR = 1.84, 95% CI: 1.29–2.62, P = 0.001) and the fully adjusted model (adjusted OR = 1.54, 95% CI: 1.02–2.34, P = 0.041). Exploratory mediation analysis further showed that the estimated indirect association related to serum TT accounted for 16.43% of the total observed association between GLM7 and PCOS ( P < 0.01). Higher GLM7 were associated with greater odds of PCOS, and the model including GLM7 showed comparatively better fit than models including conventional individual metabolic markers in the analyzed dataset. Exploratory analysis suggested that serum total testosterone statistically accounted for only a small proportion of this association. These findings suggest that GLM7 may provide an integrated measure of metabolic characteristics associated with PCOS, although further validation in prospective and independent populations is warranted.