Body composition changes and influencing factors of phase angle in maintenance hemodialysis patients with diabetic nephropathy

This retrospective longitudinal cohort study aimed to compare the clinical differences between patients with diabetic nephropathy (DN) and non-diabetic nephropathy (NDN) undergoing maintenance hemodialysis and to investigate the influencing factors and clinical significance of phase angle (PhA) in DN patients. Hemodialysis patients (n = 48), including 23 with DN and 25 with NDN, were enrolled in this study. Body composition parameters were assessed using bioelectrical impedance analysis (BIA), and various biochemical indices were collected. The follow-up period was extended to 5 years. To investigate the relationship between PhA, nutritional status, and other clinical factors, univariate analysis, principal component analysis (PCA), and logistic regression analysis were employed. Comparative analysis demonstrated significant pathophysiological divergence between groups. DN patients exhibited reduced dialysis adequacy (kt/V: 1.424 ± 0.215 vs. 1.57 ± 0.210, p = 0.021) and impaired cellular integrity evidenced by lower PhA values (4.358 ± 1.044 vs. 5.031 ± 1.23°, p = 0.048). Fluid overload patterns distinctly characterized DN patients, with elevated extracellular water ratios (ECW/TBW: 40.265 ± 1.262% vs. 39.282 ± 1.858%, p = 0.039; ECW/ICW: 63.426 ± 3.774 vs. 61.128 ± 3.244, p = 0.028). PhA demonstrated strong inverse correlations with fluid retention parameters (ECW/TBW: r = -0.954, p < 0.001; ECW/ICW: r = -0.946, p < 0.001) and positive associations with nutritional metrics including Fat-Free Mass Index (FFMI)(r = 0.496, p = 0.016), muscle circumference index (MCI) (r = 0.494, p = 0.017), Geriatric Nutritional Risk Index (GNRI) (r = 0.511, p = 0.013), and serum creatinine (Cr) levels (r = 0.448, p = 0.032). High hydration status and low muscle mass were identified as critical factors influencing the reduced PhA observed in DN patients. Significant differences in body composition and PhA exist between maintenance hemodialysis patients with DN and NDN. Low PhA is closely associated with malnutrition and can serve as an effective indicator for evaluating the nutritional status of DN patients.