Interplay between key metabolic hormones, metabolic factors, renal function, and heart rate variability in humans...

This study aimed to provide the first integrative assessment of clinical, metabolic, renal, hormonal, and heart rate variability (HRV) parameters in individuals with obesity, stratified by metabolic syndrome (MetS) and insulin resistance (IR), clarifying shared and distinct mechanisms beyond prior HRV- or hormone-focused studies. Among 45 participants with obesity (BMI ≥ 25 kg/m²), 67% had IR and 42% had MetS. Both groups exhibited increased %fat, triglyceride, leptin, and resting heart rate, with decreased QUICKI and high-density lipoprotein cholesterol (HDL-C) (p < 0.05 all). Frequency-domain HRV (VLF and LF ms²) and overall variability (SDNN) were significantly decreased in the IR group (p < 0.05 all). Leptin showed significant positive correlations with obesity, IR, and creatinine clearance (p < 0.05 all). Adiponectin exhibited positive correlations with hip circumference, HDL-C, and pNN50 while HDL-C showed negative correlations with the number of MetS criteria, obesity, IR, and leptin, but positive correlations with parasympathetic HRV (SDSD and RMSSD) (p < 0.05 all), suggesting a protective role across multiple systems. Creatinine clearance and eGFR revealed positive correlations with parasympathetic HRV (HF nu) and negative correlations with sympathetic HRV (LF nu and LF/HF ratio). In conclusion, this study underscores the complex interplay between these systems, enhancing our understanding of their shared and distinct mechanisms.