Metabolic Health is Highly Predictive of Chronic Pain Among Non-Obese Adults: Evidence from the NHANES and CHARLS Studies

OBJECTIVE: To investigate the predictive value of the estimated glucose disposal rate (eGDR) for chronic pain (CP) and to evaluate its consistency as a metabolic biomarker across diverse populations. DESIGN: A cross-sectional and retrospective cohort analysis utilizing large-scale data from the National Health and Nutrition Examination Survey (NHANES, 2001-2004) and the China Health and Retirement Longitudinal Study (CHARLS, 2011). METHODS: Multivariable logistic regression and restricted cubic splines (RCS) were employed to quantify the association between eGDR and CP. An XGBoost machine learning model was used to rank eGDR's importance relative to other metabolic factors. Subgroup and interaction analyses were conducted to identify specific populations where eGDR is most predictive. RESULTS: Higher eGDR (indicating better insulin sensitivity) was strongly and independently associated with a reduced risk of chronic pain. In the NHANES cohort, each unit increase in eGDR was associated with a 12.6% lower risk of CP (OR: 0.874, 95% CI: 0.834-0.916). Participants in the highest eGDR quartile had a 52.4% lower risk compared to those in the lowest quartile. XGBoost analysis identified eGDR as a top-ranking predictor of pain status. Critically, this inverse association was most pronounced among non-obese individuals (BMI < 30), suggesting that metabolic health is highly predictive of pain regardless of body weight. These findings were further validated in the independent CHARLS cohort, confirming the cross-populational robustness of the marker. CONCLUSION: Metabolic health, as measured by eGDR, is a powerful and consistent predictor of chronic pain in both U.S. and Chinese adults. The particularly strong association in non-obese populations underscores the importance of insulin sensitivity in pain management, beyond simple weight control. eGDR shows significant potential as a clinical biomarker for assessing chronic pain risk. CLINICAL IMPLICATIONS: Nurses can integrate eGDR assessment into metabolic health screening for patients with or at risk for chronic pain. Interventions aimed at improving insulin sensitivity-such as weight management, physical activity, and dietary counseling-should be considered as adjunct strategies in pain management nursing practice, particularly for non-obese patients.