The serum oxytocin correlated with serum leptin and body mass index in Japanese adolescents.

Oxytocin (OXT), a hypothalamic neuropeptide traditionally associated with reproduction and social bonding, has recently garnered attention for its role in regulating appetite and energy metabolism. To evaluate serum OXT levels and their association with adipokines in obese adolescents and those with type 2 diabetes mellitus (T2DM) compared to healthy controls. In this cross-sectional study, we included 27 participants-9 obese (median age [interquartile range] 10.0 [8.7-13.0] yr; men/women 3/6), 7 T2DM (16.0 [13.0-17.0] yr; 6/1), and 11 controls (10.8 [7.5-15.9] yr; 9/2). Serum OXT and adipokine levels were measured via the enzyme-linked immunosorbent assay. OXT levels were higher in patients with T2DM (130 [110-380] pg/mL) than in controls (85 [60-95] pg/mL; p = 0.002) and the obese group (125 [90-250] pg/mL) was intermediate between the two groups. Across all participants, OXT correlated positively with body mass index-standard deviation score (r = 0.51, p < 0.01) and leptin (r = 0.62, p < 0.001), and inversely with adiponectin (r = -0.39, p = 0.04). Leptin emerged as the strongest predictor of OXT variability (β = 0.53, p < 0.01). In adolescents with T2DM, serum OXT levels may reflect compensatory mechanisms in response to leptin resistance or metabolic stress.