Distinct metabolic associations of subcutaneous and visceral adipocyte morphology in women with or without obesity

This study aimed to compare subcutaneous and visceral adipocyte geometries, clinical, metabolic, hormonal, and gene expression parameters, between participants with insulin resistance (IR; n = 6) and without IR (n = 28). Additionally, correlations between these factors and adipocyte geometries were analyzed in 27 participants, including 14 with obesity and 13 without obesity, due to limited tissue availability. In a cross-sectional study at a tertiary hospital, 34 female patients undergoing intra-abdominal surgery were recruited. Participants with IR had higher serum leptin and larger visceral adipocytes but lower serum omentin and adiponectin/leptin ratio, despite comparable gene expression. Visceral adipocyte geometries showed positive correlations with IR parameters (glucose and HOMA-IR) only in individuals without obesity, but exhibited negative correlations with QUICKI, serum adiponectin, adiponectin/leptin ratio, omentin, and/or visfatin in both groups, with generally stronger correlations observed in individuals without obesity. Importantly, enlarged adipocytes were associated with lower subcutaneous and visceral adiponectin, omentin, and visfatin mRNA expression in individuals with obesity, and with higher visceral LEP mRNA expression in individuals without obesity. Multiple regression analysis identified the serum adiponectin/leptin ratio as an independent predictor of adipocyte geometries in both participants with and without obesity, and body weight in individuals without obesity. In conclusion, enlarged visceral adipocytes were more strongly associated with metabolic dysregulation in individuals without obesity, while individuals with obesity exhibited mostly weaker or no correlations, possibly due to reduced capacity for further adipocyte expansion and pre-existing metabolic impairments. The serum adiponectin/leptin ratio is a sensitive biomarker reflecting adipocyte function and morphology.