Osteoblast-secreted osteocalcin in its active (undercarboxylated) form favors insulin sensitivity in muscle, adipose tissue,
and liver, having a positive action on glycemia. In the pancreas, active osteocalcin stimulates insulin release and β-cell
proliferation. In β-cells, osteocalcin binds to its receptor Gprc6a, inducing the activation of cyclin D1 and cell-cycle progression
leading to β-cell proliferation and increase in β-cell mass.