Associations between physical fitness, insulin resistance, and estimated glomerular filtration rate in individuals with spinal cord injury

Purpose of in this study, to investigate the associations between physical fitness, insulin resistance, and estimated glomerular filtration rate (eGFR) in individuals with spinal cord injury (SCI). This cross-sectional study included 112 individuals with SCI (aged ≥ 30 years) who were receiving care at the disability welfare facilities in G and C Provinces. Physical fitness was assessed based on muscle strength, muscular endurance, flexibility, and cardiorespiratory fitness. Insulin resistance was determined using triglyceride-glucose index-body mass index, and eGFR was calculated using modification of diet in renal disease-spinal cord injury/disability. Odd ratios (ORs) and 95% confidence interval (CI) for exposure to insulin resistance and kidney dysfunction were calculated according to physical fitness. After adjusting for covariates, the low fitness groups showed a higher risk of insulin resistance (OR=5.61, 95% CI=1.01-31.04, p=0.048) and kidney function impairment (OR=6.22, 95% CI=1.01-38.21, p=0.048), compared to the high fitness group (reference, OR=1.00). In mediation analysis, after adjusting for covariates, physical fitness partially mediated the association between insulin resistance and eGFR (β=-0.042), explaining 19.9% of the total effect. Physical fitness may play a protective role against chronic kidney disease associated with high insulin resistance in individuals with SCI.