Reduced attenuation of bone resorption after oral glucose in type 2 diabetes

Abstract

To investigate the effect of oral glucose on bone resorption and osteoprotegerin (OPG) in subjects with varying degrees of glucose tolerance. In a cross-sectional study, 163 postmenopausal women aged 50-88 years without previous history of diabetes, impaired fasting glucose (IFG) or impaired glucose tolerance (IGT) were recruited. All subjects underwent a 75-g oral glucose tolerance test (OGTT) and were then classified as having normal glucose tolerance (NGT), IFG, IGT or diabetes according to American Diabetes Association (ADA) criteria. Plasma glucose, serum insulin, C-terminal telopeptide of type I collagen (CTX-I) and OPG were measured. Fasting insulin levels increased progressively from subjects with NGT, IFG/IGT to diabetes. After adjusted for age and body mass index (BMI), there was no significant difference in fasting CTX-I and OPG levels across the various degrees of glucose tolerance. After oral glucose, there was a significant decrease in serum CTX-I and OPG (P < 0.001) except for serum OPG in diabetic subjects. In addition, the percentages of change from baseline for both serum CTX-I and OPG were significantly less in diabetic subjects when compared to those in NGT subjects (-40.9% and 0.6% for diabetes and -50.2% and -10.6% for NGT, respectively). Oral glucose intake causes suppression of serum CTX-I and OPG in postmenopausal women. The effect is attenuated in women with type 2 diabetes.