Association between GLM7 glycolipid metabolism index and female infertility: A cross-sectional analysis of NHANES 2013–2020

The glycolipid metabolism 7 factors (GLM7) index is a novel composite glycolipid index that includes age, triglycerides, fasting blood glucose, body mass index, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and insulin levels. It serves as a new indicator for predicting and diagnosing diseases. However, its relationship with infertility remains unclear. This study aims to investigate the association between the GLM7 index and female infertility. A cross-sectional study was conducted using data from National Health and Nutrition Examination Survey 2013–2020. Three logistic regression models were employed to assess the correlation between the GLM7 index (as a continuous variable and stratified by tertiles) and infertility. Additionally, threshold effect analysis was performed to verify the positive correlation between the 2. Finally, interaction and stratified analyses were conducted based on age, race, household income, marital status, education level, smoking status, drinking status, and chronic disease history. A total of 3792 women were included in the analysis. When the GLM7 index was treated as a continuous variable, each 1-unit increase in GLM7 was associated with a 29% higher risk of infertility (Model 3: odds ratio [OR] = 1.29, 95% confidence interval [CI]: 1.10–1.53, P  = .002). When stratified by tertiles, compared with the lowest tertile (T1), the highest tertile (T3) was associated with a 49% increased risk of infertility after full adjustment for demographic, lifestyle, disease, and metabolic factors (OR = 1.49, 95% CI: 1.10–2.02, P -trend = .011). Restricted cubic spline analysis confirmed a nonlinear increasing trend between the GLM7 index and infertility risk (overall association P  = .001, nonlinear association P  = .009). Threshold effect analysis revealed a significant inflection point ( P  = .006): when GLM7 was below 6.84, there was a positive association with infertility (OR [95% CI]: 2.12 [1.15–3.89]). Receiver operating characteristic curve analysis evaluating the discriminative performance of the GLM7 index for female infertility demonstrated that full adjustment for confounding factors (age, race, marital status, educational attainment, smoking, alcohol consumption, diabetes, and hypertension) yielded an area under the curve of 0.68, signifying moderate discriminatory power. This cross-sectional study observes an independent nonlinear positive correlation between GLM7 index and female infertility risk among American women. The GLM7 index may act as a preliminary metabolic marker for infertility risk screening, while further prospective and external validation are required to confirm its clinical utility.