Relation between osteocalcin and the energy metabolism in obesity

Abstract

© 2019, Inst. Sci. inf., Univ. Defence in Belgrade. All rights reserved. Background/Aim. Numerous findings have indicated the potential relation between the osteocalcin, the traditional parameter of bone turnover and the regulation of energy metabolism. The aim of this study was to identify the relationship between osteocalcin and calculated indexes, which evaluate insulin sensitivity, insulin resistance and/or secretory capacity of the pancreas, in non-diabetic, obese subjects. Methods. The study included 57 (11 men and 46 women) euglycemic, obese patients (the body mass index – BMI: 41.03 ± 6.61 kg/m²) and 48 healthy individuals, age and sex matched (BMI: 23.15 ± 2.04 kg/m²). Plasma glucose and the insulin levels during the two-hour oral glucose tolerance test (OGTT) were determined in order to calculate the Homeostatic Model Assessment (HOMA) indexes (HOMA-IR, HOMA-B%), EISI (estimated insulin sensitivity index), EFP (estimated first phase) and ESP (estimated second phase). Osteocalcin was measured by using the Electro-chemiluminescence (ECLIA) methodology. Results. Statistically lower osteocalcin was found in the obese subjects (24.72 ± 9.80 vs 33.31 ± 10.89 ng/mL; p < 0.01). Тhere was a statistically significant positive correlation between osteocalcin and EISI (r = 0.340; p < 0.01). The inverse correlations were found between the osteocalcin and HOMA-IR (r =-0.276; p < 0.01), HOMA-B% (r =-0.337; p < 0.01), EFP (r =-0.332; p < 0.01) and ESP (r =-0.266; p < 0.01). Multiple regression showed that the BMI and osteocalcin have a significant inverse prediction with the EISI and HOMA-IR, but the level of prediction of the BMI was substantially higher. Conclusion. The effect of osteocalcin in the glycoregulation is evident, but its contribution is significantly smaller in relation to other obesity associated factors. Therefore, when assessing its position and the role in glycemic control it is always necessary to bear in mind that osteocalcin represents only one of the many contributing factors, some of which exhibit dominant influence than osteocalcin itself.