Association between serum osteocalcin, adiposity and metabolic risk in obese children and adolescents

Abstract

INTRODUCTION: Childhood obesity has been associated with the development of insulin resistance, potentially leading to several metabolic disorders. Osteocalcin has been reported to contribute to the regulation of glucose tolerance and insulin sensitivity. The purpose of this study was to examine the relationship between serum osteocalcin and metabolic risk factors in obese children and adolescents. MATERIAL AND METHODS: Age, gender, pubertal stage, adiposity markers (standard deviation score of body mass index: BMI-SDS, percentage of body fat, waist circumference), blood pressure, serum osteocalcin (OC), fasting plasma glucose and insulin, glycated haemoglobin level (HbA1c), insulin resistance estimated by homeostasis model assessment (HOMA-IR), lipid profile, C-reactive protein (CRP), fibrinogen (FB), white blood cell count (WBC) and 25-hydroxyvitamin D (25-OH-D) were evaluated in 142 obese children and adolescents. Stepwise multiple regression analysis was used to determine the relationship between serum osteocalcin and metabolic risk parameters. RESULTS: Mean serum osteocalcin level was 72.0 ± 20.5 μg/L (range: 16.8-181.5 µg/L). After adjustment for multiple potential confounders, serum osteocalcin concentration was inversely associated with adiposity markers as well as HOMA-IR, HbA1c, triglycerides, CRP, FB and positively with 25-OH-D and HDL-cholesterol. In stepwise multiple linear regression analysis adjusted for age, gender and pubertal stage, osteocalcin was significantly negatively related to HOMA-IR, triglycerides and waist circumference. CONCLUSIONS: Serum osteocalcin concentration is associated with blood markers of dysmetabolic phenotype and measures of adiposity, suggesting that osteocalcin is important not only for bones but also for glucose and fat metabolism as early as during childhood.