title: Serum undercarboxylated osteocalcin levels are inversely associated with glycemic status and insulin resistance in an elderly Japanese male population: Fujiwara-kyo Osteoporosis Risk in Men (FORMEN) Study.
abstract: CONCLUSIONS
  Recent animal studies have demonstrated that undercarboxylated osteocalcin upregulates insulin secretion via osteoblast-insulin signaling. However, it remains unclear whether such a pathway exists in humans. This study showed that serum undercarboxylated osteocalcin levels were inversely associated with fasting plasma glucose, hemoglobin A(1c), and homeostasis model assessment of insulin resistance (HOMA-IR) levels in community-dwelling elderly Japanese men.
  
  
  BACKGROUND
  Undercarboxylated osteocalcin (ucOC) was reported to increase insulin secretion and improve glucose tolerance via osteoblast-insulin signaling in animal-based studies. Whether this pathway also exists in humans is unknown. We aimed to clarify whether serum ucOC levels are associated with glycemic status and insulin resistance in the general Japanese population.
  
  
  METHODS
  We included 2,174 Japanese men (≥65 years) who were able to walk without aid from others and lived at home in four cities of Nara Prefecture. We excluded participants with a history of diseases or medications that affect bone metabolism, other than type 2 diabetes mellitus (T2DM). Fasting plasma glucose, glycated hemoglobin A(1c), and HOMA-IR levels were determined as outcome measures.
  
  
  RESULTS
  Of the 1,597 participants included in the analysis, both intact OC (iOC) and ucOC levels showed significant inverse correlations with all outcome measures, even after adjusting for potential confounders. Mean values of outcome measures showed a significant decreasing trend with higher quintiles of iOC or ucOC after adjusting for confounders. This trend remained significant for ucOC quintiles after further adjustment for iOC levels, but was not significant for iOC quintiles after adjusting for ucOC levels. These results were attenuated, but still apparent, after excluding participants receiving drug therapy for T2DM.
  
  
  CONCLUSIONS
  Levels of ucOC, but not iOC, were inversely associated with glycemic index and insulin resistance in a population of Japanese men. These findings will need to be confirmed with longitudinal studies.
authors: Department of Public Health, Kinki University Faculty of Medicine, 377-2 Oono-higashi, Osaka-Sayama, Osaka 589-8511, Japan. masa@med.kindai.ac.jp
authors: M
authors: M
authors: Iki
authors: J
authors: J
authors: Tamaki
authors: Y
authors: Y
authors: Fujita
authors: K
authors: K
authors: Kouda
authors: A
authors: A
authors: Yura
authors: E
authors: E
authors: Kadowaki
authors: Y
authors: Y
authors: Sato
authors: J S
authors: JS
authors: Moon
authors: K
authors: K
authors: Tomioka
authors: N
authors: N
authors: Okamoto
authors: N
authors: N
authors: Kurumatani
mesh_terms: D000135:Acid Phosphatase / Q000097:blood; D000368:Aged; D000886:Anthropometry / Q000379:methods; D001786:Blood Glucose / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000453:epidemiology; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D007527:Isoenzymes / Q000097:blood; D007564:Japan / Q000453:epidemiology; D008019:Life Style; D008297:Male; D015675:Osteocalcin / Q000097:blood*; D015398:Signal Transduction / Q000502:physiology; D000071681:Tartrate-Resistant Acid Phosphatase
chemical_list: D000135:Acid Phosphatase; D001786:Blood Glucose; D006442:Glycated Hemoglobin; D007527:Isoenzymes; D015675:Osteocalcin; D000071681:Tartrate-Resistant Acid Phosphatase; C517652:hemoglobin A1c protein, human