The relationship of serum 25-hydroxyvitamin D with glucose homeostasis in obese children and adolescents in Zhejiang, China

Abstract

Background: Evidence of the association between vitamin D, insulin resistance and oral disposition index (oDI) in obese children and adolescents is limited. Objective and hypotheses: We investigated serum 25(OH)D levels in obese children and adolescents in Zhejiang, China, and determined the relationship between serum 25(OH)D and glucose metabolism. Method: A cross-sectional design was used. All together 348 obese and 445 non-obese children and adolescents (aged from 6 to 16 years old) were enrolled in this study. Obese children were divided into four subgroups: normal glucose tolerance (NGT), isolated impaired fasting glucose (IFG), isolated impaired glucose tolerance (IGT), combined IFG and ITG (IFGCITG) according to the oral glucose tolerance test. We measured serum 25(OH)D levels and calculated the homeostasis model of insulin resistance (HOMA-IR), the whole body insulin sensitivity index (WBISI), the product of beta-cell function and insulin sensitivity by the disposition index (DI). Results: The levels of 25(OH)D in obese group were significantly lower than those of non-obese group; serum 25(OH)D level in obese with NGT group was higher than that of the other three subgroups, and it was significantly inversed with LogHOMA-IR (r=-0.114, P=0.035), positively correlated with LogWBISI, LogHOMA0DI after control for age, sex, season, puberty stage (r=0.111, P=0.040; r=0.122, P=0.024). Obese patients with vitamin D deficiency have a significantly higher risk of disturbing the glucose metabolism, such as IFG, ITG, IFG plus ITG, either IFG or ITG, for its OR 3.198 (95%CI 1.467-6.97), 5.443 (95%CI 1.863-15.897), 5.560 (95%CI 1.212-25.502), 4.007 (95%CI 2.017-7.962). Conclusion: 25(OH)D deficiencies or insufficiency are common in obese children and adolescents in Zhejiang, China. Obese patients with 25(OH)D deficiency (<30 nmol/l) are at higher risk for abnormal glucose metabolism.