title: Decreased undercarboxylated osteocalcin in children with type 2 diabetes mellitus.
abstract: BACKGROUND
  Osteocalcin (OC) is a bone-specific protein secreted by osteoblasts and often used as a bone formation biomarker. OC undergoes post-translational carboxylation to yield carboxylated osteocalcin (Gla-OC) and undercarboxylated osteocalcin (uc-OC) molecules. The aim of this study was to explore the association between bone and glucose metabolism by evaluating OC, ionized cations, and markers of glucose metabolism in children with obesity and type 2 diabetes mellitus (DM2).
  
  
  METHODS
  The subjects were nine children with DM2 [six males, three females; age 15.7±4.1 years; duration of disease 3.2±1.2 years], 18 children with simple obesity [12 males, six females; age 12.6±4.1 years], and 12 controls [eight males, four females; age 12.3±3.2 years]. Serum Gla-OC and uc-OC levels were determined using an enzyme-linked immunosorbent assay (ELISA).
  
  
  RESULTS
  Patients with DM2 (0.65±0.46 ng/mL), but not with obesity (1.11±0.55 ng/mL), had lower uc-OC levels than controls (1.25±0.49 ng/mL). Serum uc-OC was negatively correlated with mean serum glucose levels (r=-0.447, p=0.013) and hemoglobin A1c (HbA1c) (r=-0.455, p=0.012) in all subjects. Serum Gla-OC was correlated with serum alkaline phosphatase (r=0.601, p<0.001) and inorganic phosphorus (r=0.686, p<0.001), yet negatively correlated with age (r=-0.383, p=0.030). Mean serum ionized magnesium was lower in DM2 subjects than in controls. Mean serum ionized calcium was higher in obese subjects than in controls. In all subjects, mean serum ionized magnesium was negatively correlated with mean serum glucose levels.
  
  
  CONCLUSIONS
  Osteoblast-derived protein OC, especially uc-OC, may have a role in the pathophysiology of diabetes by being associated with blood glucose homeostasis.
authors.forename: Junji
authors.initials: J
authors.lastname: Takaya
authors.forename: Yuko
authors.initials: Y
authors.lastname: Tanabe
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kuroyanagi
authors.forename: Kazunari
authors.initials: K
authors.lastname: Kaneko
mesh_terms: D000293:Adolescent; D015415:Biomarkers / Q000378:metabolism*; D001786:Blood Glucose / Q000032:analysis; D002264:Carboxylic Acids / Q000737:chemistry*; D016022:Case-Control Studies; D002648:Child; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology / Q000503:physiopathology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D008297:Male; D009765:Obesity / Q000150:complications; D015675:Osteocalcin / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D002264:Carboxylic Acids; D006442:Glycated Hemoglobin; D015675:Osteocalcin