Background: Osteocalcin (OC) is an osteoblast derived marker of bone turnover, but it has also been linked to glucose metabolism. Specifically, the undercarboxylated form of OC has been proposed to act as a hormone that links bone to glucose homeostasis.
Objective and hypotheses: Our aim was to study whether serum total OC associates with insulin sensitivity in 12-year-old children.
Subjects and methods: A total of 192 children (109 girls) were studied at the mean age of 12.25 years (range 12.0112.73). Seventy-eight of them had been born as appropriate for gestational age (AGA), 70 as small for gestational age (SGA, birth weight or length <−2 SDS), and 44 from preeclamptic (PRE) pregnancies as AGA. Pubertal development was assessed according to the Tanner scale. Fasting serum total OC, high molecular weight adiponectin (HMW-adipo), leptin, insulin, IGF1, IGFBP1, IGFBP3, and blood glucose were measured. Quantitative Insulin Sensitivity Check Index (QUICKI) was calculated. MannWhitney U and Spearman tests, and logistic regression statistical analyses were used.
Results: The means of serum OC, HMW-adipo, leptin, insulin, IGF1, IGFBP1, IGFBP3, blood glucose, and QUICKI did not differ between the children born as SGA, AGA or from PRE pregnancies (P>0.05 for all). In the whole study population, serum OC correlated negatively with BMI, leptin, HMW-adipo, and positively with IGF1, IGFBP1, and IGFBP3 (P<0.01 for all). The highest OC concentrations were found in midpuberty (Tanner B/G stage 3). The children in the highest OC tertile (n=64) had lower leptin, HMW-adipo and BMI, higher IGF1, IGFBP1, and IGFBP3 than the subjects in the lowest OC tertile (P<0.01 for all). The QUICKI means did not differ between these OC tertiles. In a logistic regression analysis, low leptin (P=0.008), HMW-adipo (P=0.040), and high IGF1 (P=0.021) associated independently with high OC (adjusted by BMI, pubertal stage, sex, SGA, or maternal PRE pregnancy history).
Conclusion: Serum OC was not associated with insulin sensitivity (QUICKI) or history of SGA. Instead, high OC was associated with low leptin and HMW-adipo. The relationship between high OC and IGF1 may reflect the fast pubertal growth phase.
20 - 22 Sep 2014
European Society for Paediatric Endocrinology