title: Association between osteocalcin and glucose metabolism: a meta-analysis.
abstract: This meta-analysis aimed to investigate the associations between osteocalcin (Ocn) and fasting plasma glucose (FPG) and glycated hemoglobin A1c (HbA1c). It was revealed that both total Ocn and undercarboxylated Ocn (unOcn) were negatively related with FPG and HbA1c, and the association of unOcn with FPG was more pronounced in men.
  
  
  BACKGROUND
  The aim of this study was to investigate the strength of associations between Ocn and FPG and HbA1c using a meta-analysis approach.
  
  
  METHODS
  A search was carried out using the databases of PubMed, ISI Web of Science, and the Cochrane library from 2007 to 2014 to identify related studies. A pooled effect size with 95 % confidence intervals (CI) was derived.
  
  
  RESULTS
  The meta-analysis included 39 studies involving 23,381 participants. The overall correlation was -0.16 (95 % CI, -0.19 to -0.14) between total Ocn (tOcn) and FPG and -0.15 (95 % CI, -0.20 to -0.11) between undercarboxylated Ocn (unOcn) and FPG. In the analysis of the association between Ocn and HbA1c, the pooled correlation was -0.16 (95 % CI, -0.18 to -0.14) for tOcn and -0.16 (95 % CI, -0.23 to -0.08) for unOcn. The magnitude of the correlation between unOcn and FPG is significantly higher in men than in women (r = -0.18, 95 % CI, -0.21 to -0.14; r = -0.09, 95 % CI, -0. 13 to -0.05, respectively; P for interaction < 0.05). Similar trend was also found between unOcn and HbA1c but without significance (for men, r = -0.19, 95 % CI, -0.24 to -0.14; for women, r = -0.09, 95 % CI, -0.22 to 0.04, respectively; P for interaction > 0.05). No indication of significant publication bias was found in any method.
  
  
  CONCLUSIONS
  This meta-analysis demonstrated that both unOcn and tOcn were similarly and negatively correlated with FPG and HbA1c in humans. The negative correlations between unOcn and glucose metabolism appear to be more pronounced in men than in women.
authors.affiliation: Department of Endocrine and Metabolic Diseases, Rui-jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China.|Shanghai Institute of Endocrine and Metabolic Diseases, Shanghai, China.
authors.forename: D-M
authors.initials: DM
authors.lastname: Liu
authors.affiliation: Department of Endocrine and Metabolic Diseases, Rui-jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China.|Shanghai Institute of Endocrine and Metabolic Diseases, Shanghai, China.
authors.forename: X-Z
authors.initials: XZ
authors.lastname: Guo
authors.affiliation: Institut de Recherches Cliniques de Montréal (IRCM) Department of Microbiology and Immunology, University of Montreal and Division of Experimental Medicine, McGill University, Montreal, QC, H2W 1R7, Canada.
authors.forename: H-J
authors.initials: HJ
authors.lastname: Tong
authors.affiliation: Department of Endocrine and Metabolic Diseases, Rui-jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China.|Shanghai Institute of Endocrine and Metabolic Diseases, Shanghai, China.
authors.forename: B
authors.initials: B
authors.lastname: Tao
authors.affiliation: Department of Endocrine and Metabolic Diseases, Rui-jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China.|Shanghai Institute of Endocrine and Metabolic Diseases, Shanghai, China.
authors.forename: L-H
authors.initials: LH
authors.lastname: Sun
authors.affiliation: Department of Endocrine and Metabolic Diseases, Rui-jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China.|Shanghai Institute of Endocrine and Metabolic Diseases, Shanghai, China.
authors.forename: H-Y
authors.initials: HY
authors.lastname: Zhao
authors.affiliation: Department of Endocrine and Metabolic Diseases, Rui-jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China. guangning@medmail.com.cn.|Shanghai Institute of Endocrine and Metabolic Diseases, Shanghai, China. guangning@medmail.com.cn.
authors.forename: G
authors.initials: G
authors.lastname: Ning
authors.affiliation: Department of Endocrine and Metabolic Diseases, Rui-jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China. ljmhh@sh163.net.|Shanghai Institute of Endocrine and Metabolic Diseases, Shanghai, China. ljmhh@sh163.net.
authors.forename: J-M
authors.initials: JM
authors.lastname: Liu
mesh_terms: D001786:Blood Glucose / Q000378:metabolism*; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D015675:Osteocalcin / Q000097:blood*; D017594:Publication Bias; D012680:Sensitivity and Specificity
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; D015675:Osteocalcin; C517652:hemoglobin A1c protein, human
keywords: Fasting plasma glucose; Glycated hemoglobin A1c; Meta-analysis; Osteocalcin