Obesity, hyperglycemia and endothelial function in inner city Bronx adolescents: a cross-sectional study

BACKGROUND: Along with the rise in obesity, cardiovascular disease (CVD) has become the major cause of death in developed countries. Although overt coronary heart disease rarely manifests during childhood, atherosclerosis can begin by the second decade of life. Therefore, identifying reliable risk markers of early vascular disease in childhood could be important. Alteration in endothelial function (EF) is an early preclinical marker of the atherosclerotic process and can be assessed non-invasively using reactive hyperemia peripheral arterial tonometry (RH-PAT). The purpose of this study was to investigate if obesity in children is associated with lower EF as measured with RH-PAT, and if obese children with impaired glucose regulation have further impairment in RH-PAT measured EF compared to obese children with normal glucose tolerance. METHODS: Cardiovascular risk factors, adipocytokines and EF using RH-PAT were evaluated in lean (n = 14) and obese (n = 37) adolescents (age 12–18 years). Based on an oral glucose tolerance test, the obese group was subdivided into: obese with normal (NGT, n = 22) and obese with impaired glucose regulation (IGR, n = 15). RESULTS: RH-PAT score was lower in obese subjects compared to lean controls (1.70 ± 0.02 vs. 1.98 ± 0.09, P = 0.02), indicating worse EF. This difference remained significant when adjusted for age, sex and ethnicity (P = 0.02). We observed a pattern of worsening EF with increasing metabolic burden, with RH-PAT scores of 1.98 ± 0.09,1.73 ± 0.08 and 1.65 ± 0.12 in the lean, obese-NGT and obese-IGR groups, respectively, p(trend) = 0.03. Obese subjects were more insulin resistant [higher HOMA] (p = 0.03), and had higher levels of leptin (p = 0.004), hsCRP (p = 0.0004), and TNF-α (p = 0.03) compared to lean subjects. Adjusting for insulin resistance and adipocytokines substantially attenuated the obesity association with RH-PAT, suggesting that insulin resistance and inflammation may mediate the association of EF with obesity. CONCLUSIONS: Risk factors for adult cardiovascular disease, including impaired EF, insulin resistance and inflammation, are evident in obese adolescents. Whether early detection of these cardiovascular risk factors will be useful for informing interventions to prevent disease progression needs further study. TRIAL REGISTRATION: Clinical Trials Identifier: NCT01879033