Systemic inflammatory indices and glucose homeostasis in children with obesity: evidence from oral glucose tolerance testing.

UNLABELLED: The systemic immune-inflammation index (SII) and pan-immune-inflammation value (PIV) are emerging biomarkers of chronic low-grade inflammation. This study aimed to evaluate their association with glucose metabolism abnormalities in children with obesity. In this retrospective cross-sectional study, children and adolescents with obesity who underwent an oral glucose tolerance test (OGTT) were included. SII and PIV were calculated from complete blood counts. ANCOVA was used to adjust for body mass index standard deviation score (BMI-SDS), age, sex, and pubertal status, and effect sizes were estimated. A total of 238 participants were analyzed (154 normoglycemic, 84 dysglycemic), most of whom were pubertal (92%). BMI-SDS showed a significant positive correlation with both SII (r = 0.236, p < 0.001) and PIV (r = 0.279, p < 0.001). No significant associations were found between inflammatory indices and metabolic parameters, including HbA1c, lipid profile, HOMA-IR, Matsuda index, or insulinogenic index (p > 0.05). After adjustment for BMI-SDS, age, sex, and pubertal status, SII levels remained significantly higher in the normoglycemic group (679.86 vs. 553.06, p = 0.025), with a small-to-moderate effect size (Cohen's d = 0.341; η2 = 0.021). PIV showed a similar trend without statistical significance. CONCLUSION: Higher SII values were observed in the normoglycemic group; however, the explanation for this unexpected association remains uncertain. The findings do not support the use of SII as a diagnostic or screening biomarker for dysglycemia. WHAT IS KNOWN: • Chronic low-grade inflammation contributes to obesity-related metabolic dysfunction. SII and PIV have been associated with metabolic abnormalities, but pediatric data based on OGTT-defined glucose tolerance are limited. WHAT IS NEW: • SII was unexpectedly higher in normoglycemic participants after adjustment, whereas PIV was not independently associated with dysglycemia. Neither index correlated with OGTT-derived insulin sensitivity or early insulin secretion, limiting their clinical utility for detecting dysglycemia.