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

Objective To investigate the effect of oral glucose on bone resorption and osteoprotegerin (OPG) in subjects with varying degrees of glucose tolerance. Design and Patients 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. Measurements Plasma glucose, serum insulin, C-terminal telopeptide of type I collagen (CTX-I) and OPG were measured. Results 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). Conclusions Oral glucose intake causes suppression of serum CTX-I and OPG in postmenopausal women. The effect is attenuated in women with type 2 diabetes.