title: Association between low C-peptide and low lumbar bone mineral density in postmenopausal women without diabetes.
abstract: 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.
  
  
  BACKGROUND
  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.
  
  
  METHODS
  Participants underwent a bone mineral density evaluation by DXA and biochemical analysis including the C-peptide assay.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Clinical Nutrition Unit, Care Center in Menopause, Department of Medical and Surgical Science, University Magna Grecia of Catanzaro, Campus Universitario Germaneto, Viale S. Venuta, 88100, Catanzaro, Italy, tmontalcini@unicz.it.
authors.forename: T
authors.initials: T
authors.lastname: Montalcini
authors.forename: P
authors.initials: P
authors.lastname: Gallotti
authors.forename: A
authors.initials: A
authors.lastname: Coppola
authors.forename: V
authors.initials: V
authors.lastname: Zambianchi
authors.forename: M
authors.initials: M
authors.lastname: Fodaro
authors.forename: E
authors.initials: E
authors.lastname: Galliera
authors.forename: M G
authors.initials: MG
authors.lastname: Marazzi
authors.forename: S
authors.initials: S
authors.lastname: Romeo
authors.forename: S
authors.initials: S
authors.lastname: Giannini
authors.forename: M M
authors.initials: MM
authors.lastname: Corsi Romanelli
authors.forename: A
authors.initials: A
authors.lastname: Pujia
authors.forename: C
authors.initials: C
authors.lastname: Gazzaruso
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000368:Aged; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D015519:Bone Density / Q000502:physiology; D001851:Bone Diseases, Metabolic / Q000097:blood* / Q000503:physiopathology; D002096:C-Peptide / Q000097:blood / Q000172:deficiency*; D003430:Cross-Sectional Studies; D003920:Diabetes Mellitus / Q000097:blood; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000503:physiopathology*; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000097:blood / Q000503:physiopathology; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D002096:C-Peptide