c-peptide and Osteoporosis--Postmenopausal

Insulin sensitivity (Si), glucose tolerance, and lipid metabolism were investigated in osteopenic postmenopausal women before and after 6 months of treatment with raloxifene (60 mg/d) or placebo. In a group of women (n = 34), glucose metabolism was evaluated by means of an oral glucose tolerance test (75 g). In another group of women (n = 24), Si and peripheral glucose utilization not dependent on insulin were evaluated by means of a frequently sampled iv glucose tolerance test associated with the minimal model method. No metabolic modification was observed in women receiving placebo. Raloxifene did not significantly modify high density lipoprotein-cholesterol and triglycerides, whereas it significantly decreased low density lipoprotein (LDL) cholesterol (4.84 +/- 0.34 mmol/liter vs. 3.83 +/- 0.49 mmol/liter; P = 0.014) and LDL/high density lipoprotein cholesterol ratio (3.21 +/- 0.31 mmol/liter vs. 2.46 +/- 0.44 mmol/liter; P = 0.012). Fasting levels and responses to the oral glucose tolerance test of glucose, insulin, C-peptide, and C-peptide/insulin were not modified by raloxifene. Similarly, raloxifene did not modify Si (4.22 +/- 4.1 vs. 5.13 +/- 1.75), or insulin (0.025 +/- 0.003 vs. 0.019 +/- 0.002). The present data show that in osteopenic postmenopausal women raloxifene reduces LDL levels but does not modify insulin sensitivity and glucose metabolism.

Topics: Blood Glucose; Bone Diseases, Metabolic; C-Peptide; Estradiol; Female; Follicle Stimulating Hormone; Glucose Tolerance Test; Humans; Insulin; Italy; Middle Aged; Osteoporosis, Postmenopausal; Placebos; Postmenopause; Raloxifene Hydrochloride; Selective Estrogen Receptor Modulators; White People

C-peptide has been shown to exert several, previously unknown, biological effects. A recent cross-sectional study demonstrated an association between low C-peptide serum levels and low lumbar bone density of postmenopausal women not affected by diabetes. To date, very little research attention has been directed toward the association between C-peptide and osteoporotic fractures. To contribute toward filling this gap, we investigated the association between C-peptide and fractures in postmenopausal women.. A cohort of 133 non-diabetic postmenopausal women with and without a history of fractures was evaluated in this cross-sectional investigation. Standardized interviews were performed to gather information on the patients' fracture history. All of the participants underwent a bone mineral density assessment by DXA, radiographs, and a serum C-peptide measurement.. Thirty-four women presented fractures. Bivariate analysis revealed an inverse correlation between C-peptide and fractures (r = -0.27, p = 0.002). A significant difference in mean C-peptide levels was also found between women with vs. without fractures (p = 0.01, adjusted for age, BMI and glucose). Logistic regression analysis showed that C-peptide levels, femoral and vertebral BMD were all negatively associated with fracture status (B = -1.097, ES = 0.401, p = 0.006, 95% CI 0.15-0.73; B = -15.6, SE = 4.17, p < 0.001, CI 0.001-0.002; B = -24.8, SE = 5.23, p < 0.001, CI 0001-0.002; respectively).. This study confirms an inverse association between serum C-peptide levels and a history of fractures in postmenopausal women without diabetes. These results suggest that C-peptidemay exert an effect on bone mineral density. However, further large-scale studies are needed to corroborate this finding and investigate the potential underlying mechanisms involved.

Topics: Aged; Biomarkers; Bone Density; C-Peptide; Cross-Sectional Studies; Diabetes Mellitus; Female; Follow-Up Studies; Humans; Italy; Middle Aged; Osteoporosis, Postmenopausal; Osteoporotic Fractures; Postmenopause; Prevalence; Prognosis; Risk Factors

In this population-based, cross-sectional study in Italian postmenopausal females not affected by diabetes, we showed a link between serum C-peptide and lumbar bone mineral density, suggesting that C-peptide exerts an insulin-independent effect on bone mass.. It is well known that type 1 (T1) diabetes, characterized by insulin and C-peptide deficiency, is associated with a low lumbar bone mineral density and an increased risk for fracture. While a role for insulin in the pathogenesis of osteoporosis has been demonstrated, the association between C-peptide and the bone mineral density has not been investigated. We conducted a study in a cohort of 84 postmenopausal women without diabetes to clarify the association between serum C-peptide and the lumbar bone mineral density.. Participants underwent a bone mineral density evaluation by DXA and biochemical analysis including the C-peptide assay.. rteen percent of the population had osteoporosis and 38% had osteopenia. With ANOVA test, we showed that women with the lowest C-peptide concentration had lower lumbar mineral density in comparison to those in all other C-peptide concentration group (p = 0.02 among groups after adjustment). The univariate and multivariate analysis showed that C-peptide was positively associated with both lumbar T-score and Z-score besides other well-known factors like age (with T-score p < 0.001; beta = -0.38) and BMI (with T-score p = 0.009; beta = 0.34), while insulin was not correlated with the lumbar bone mineral density. The area under the receiver operating characteristic (ROC) curve for C-peptide to predict the absence of lumbar osteoporosis was 0.74 (SE = 0.073; p = 0.013).. These results suggest that C-peptide may exert an insulin- and BMI-independent effect on lumbar bone mineral density and that further large-scale studies are needed in order to clarify its role in bone mineralization especially in subjects without diabetes.

Topics: Absorptiometry, Photon; Aged; Biomarkers; Body Mass Index; Bone Density; Bone Diseases, Metabolic; C-Peptide; Cross-Sectional Studies; Diabetes Mellitus; Female; Humans; Lumbar Vertebrae; Middle Aged; Osteoporosis, Postmenopausal; Sensitivity and Specificity