Lower serum osteocalcin concentrations in patients with type 2 diabetes and relationships with vascular risk factors among patients with coronary artery disease.

BACKGROUND: Lower serum concentrations of the osteoblast-derived protein, osteocalcin, have been associated with poorer glycemic control, insulin resistance and atherosclerosis, and with the development of type 2 diabetes (T2DM). METHODS: This study compares concentrations of two physiological forms of osteocalcin, carboxylated (cOCN) and uncarboxylated (unOCN), between participants with T2DM (n = 20) and age-, gender- and body mass index (BMI)-matched participants without T2DM (n = 40) among patients with coronary artery disease (CAD), and it explores relationships between osteocalcin concentrations and cardiovascular risk factors. RESULTS: Concentrations of unOCN (2.71 ±â€¯1.86 vs. 4.70 ±â€¯2.03 ng/mL; t = -3.635, p = 0.001) and cOCN (8.70 ±â€¯2.27 vs. 10.77 ±â€¯3.69 ng/mL; t = -2.30, p = 0.025) were lower in participants with T2DM. In participants without T2DM, concentrations of cOCN were associated with fitness (VO2Peak rho = 0.317, p = 0.047) and lower body fat (rho = -0.324, p = 0.041). In participants with T2DM, lower unOCN was associated with HbA1c (rho = -0.516, p = 0.020). Higher body mass was associated with higher unOCN (rho = 0.423, p = 0.009) in participants without T2DM, but with lower concentrations of both unOCN (rho = -0.590, p = 0.006) and cOCN (rho = -0.632, p = 0.003) in participants with T2DM. CONCLUSION: In patients with CAD, lower osteocalcin concentrations were related to type 2 diabetes, and to adverse fitness, metabolic and obesity profiles.