Relation between osteocalcin and the energy metabolism in obesity

Background/aims: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 (BMI:41,03 ± 6,61kg/m2) and 48 healthy individuals, age and sex matched (BMI:23,15±2,04kg/m2). Plasma glucose and insulin levels during two hour oral glucose tolerance test (OGTT) were determined in order to calculate HOMA indexes (HOMA-IR, HOMA-B%), EISI (estimated insulin sensitivity index), EFP (estimated first phase) and ESP (estimated second phase). Osteocalcin was measured using Electrochemiluminescence (ECLIA) methodology. Results: Statistically lower osteocalcin was found in 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, BMI and osteocalcin have a significant inverse prediction with EISI and HOMA-IR, but the level of prediction of BMI was is substantially higher. Conclusion: The effect of osteocalcin in the glyco-regulation is evident, but its contribution is significantly smaller in relation to primarily, obesity associated factors. Therefore, when assessing the position and the role in glycemic control, aways must bear in mind that osteocalcin represents only one of the many contributing factors, some of which exhibit dominant influence then osteocalcin itself.