Changes of osteoprotegerin before and after insulin therapy in type 1 diabetic patients

Abstract

To investigate the relationship between the plasma osteoprotegerin (OPG) level and endothelium-dependent arterial dilation in type 1 diabetic patients. Sandwich ELISA method was used to detect the plasma OPG levels of 22 newly diagnosed type 1 diabetic patients before and 6 months after treatment and of 28 healthy subjects. All patients were then given insulin therapy for 6 months. High resolution ultrasound was used to measure the brachial artery diameter at rest, after reactive hyperemia and after sublingual administration of glyceryltrinitrate (GTN). The plasma OPG level of the patients before treatment was 3.09 ng/L +/- 0.70 ng/L, significantly higher than that of the healthy controls (2.07 ng/L +/- 0.75 ng/L, P < 0.001). After 6 months treatment, the OPG level of the patients decreased to 2.58 ng/L +/- 0.59 ng/L, significantly lower than that before treatment (P < 0.001). The flow-mediated endothelium-dependent arterial dilation in the patients before treatment was 3.35% +/- 0.67%, significantly lower than that of the healthy controls (5.17% +/- 0.83%, P < 0.001), and was increased to 4.27% +/- 0.63% after 6 months treatment, significantly higher than that before (P < 0.001). Multivariate analysis showed that OPG level was significantly associated with endothelium-dependent arterial dilation, fasting blood glucose (FBG), hemoglobin A1c (HbA1c), and ultra-sensitive C-reactive protein (CRP) at baseline (all P < 0.01). The absolute change in OPG level was significantly correlation with the changes in endothelium-dependent arterial dilation, FBG, HbA1c, and CRP in the diabetic patients during the course of treatment (all P < 0.01). Plasma OPG level is elevated in newly diagnosed diabetic patients, and the plasma OPG level is significantly associated with endothelial function.