Plasma concentrations of osteoprotegerin during normoand hyperglycaemic clamping

Objective. Plasma levels of osteoprotegerin (OPG) are elevated in subjects with diabetes as well as in non-diabetic subjects with cardiovascular disease. In previous studies a positive correlation was found between plasma levels of OPG and markers of glycaemic control in diabetic subjects. The aim of the present study was to examine the effect of acute hyperglycaemia on plasma levels of OPG in nondiabetic subjects. Material and methods. Nine healthy, lean, male subjects were examined in a randomized, blinded, cross-over study design during hyperglycaemic (plasma glucose=15 mmol/L, study H) as well as during euglycaemic (plasma glucose=5 mmol/L, study E) conditions. Blood samples were collected at baseline and at t=240 min. Results. Plasma OPG decreased slightly during study H (1.26 +/- 0.39 versus 1.19 +/- 0.35 ng/mL, p<0.05), whereas the level did not change significantly during study E (1.40 +/- 0.46 ng/mL versus 1.57 +/- 0.50 ng/mL, NS). The decrease in plasma OPG during hyperglycaemia did not correlate with the change in plasma glucose but correlated significantly with changes in serum insulin (r=-0.70, p=0.038). Conclusions. Acute hyperglycaemia does not seem to increase plasma levels of OPG in non-diabetic subjects, whereas hyperinsulinaemia may suppress plasma levels of OPG. This finding indicates that the elevated plasma levels of OPG observed in diabetic subjects with poor metabolic control cannot be ascribed to hyperglycaemia per se.