Elsevier

Metabolism

Volume 60, Issue 8, August 2011, Pages 1186-1192
Metabolism

Low serum osteocalcin level is a potential marker for metabolic syndrome: results from a Chinese male population survey

https://doi.org/10.1016/j.metabol.2011.01.002Get rights and content

Abstract

Osteocalcin has been recognized as a bone-derived hormone to regulate energy metabolism recently. Little is known about the role of osteocalcin as regards metabolic syndrome (MetS) in a Chinese population. Components of MetS, osteocalcin, body mass index (BMI), and prevalence of MetS were assessed in 2344 men aged 20 to 69 years who participated in the population-based Fangchenggang Area Male Health and Examination Survey, which was carried out in Guangxi province of China from September 2009 to December 2009. Osteocalcin had a statistically significant positive correlation with high-density lipoprotein cholesterol and a negative relationship with blood pressure, glucose, triglycerides, waist circumference, and BMI after adjustment for age (all P < .001). The strongest correlation was observed between osteocalcin and BMI (r = −0.26). In a multivariate analysis, decreased odds ratios (ORs) for the MetS and its components as well were observed from the first to the fourth osteocalcin quartiles. After adjustment for BMI, the OR decreased substantially. Statistically significant difference still existed in MetS (OR, 1.77; 95% confidence interval [CI], 1.10-2.85), hypertriglyceridemia (OR, 1.66; 95% CI, 1.22-2.27), hyperglycemia (OR, 1.42; 95% CI, 1.05-1.92), and low high-density lipoprotein cholesterol (OR, 1.83; 95% CI, 1.03-3.24) when these risks were compared in the lowest quartile of osteocalcin levels with those in the highest quartile. In a Chinese male population, we firstly identified an inverse association of serum osteocalcin levels with MetS, independent from the well-known MetS risk factors. This may represent a further mechanism for the elevated cardiovascular disease or type 2 diabetes mellitus risk.

Introduction

Metabolic syndrome (MetS) is a cluster of abnormal metabolic conditions that increases the risk of cardiovascular disease [1] and type 2 diabetes mellitus [2]. Typically, it includes abdominal obesity, dyslipidemia, hyperglycemia, and elevated blood pressure [3]. Individuals with MetS are associated with approximately 5- and 2-fold increased risk for type 2 diabetes mellitus [4] and cardiovascular disease [5], respectively. In addition, MetS is a considerable public health issue in both developed and developing countries now [6], [7], [8].

On the other hand, osteocalcin has recently been recognized as a bone-derived hormone to regulate energy metabolism. In 2007, Lee et al [9] found that, compared with wild-type mice, osteocalcin−/− knockout mice had an abnormal amount of fat mass and an increase in serum triglycerides, and exhibited impaired insulin secretion, insulin resistance, and glucose intolerance. Expression of insulin target genes in liver and muscle (Fox a2, Mcad, Nrft, etc) and adiponectin gene in adipose all decreased. In vitro, insulin expression was induced when pancreatic β-cells were cocultured with bacterially produced recombinant osteocalcin (3 ng/mL) [9]. Furthermore, osteocalcin−/− mice had higher insulin and lower glucose levels when injected with recombinant osteocalcin [9]. Similar results also appear in a population-based study. In humans, significant inverse associations of osteocalcin with insulin resistance, blood glucose, adiposity, and triglycerides have been described [10], [11], [12], [13]. One recent study in blacks and non-Hispanic whites reported a negative relationship between serum osteocalcin and the presence of MetS [14]. However, this study was conducted in an older, predominantly hypertensive cohort, rather than younger and mainly normotensive adults. Besides, osteocalcin levels varied depending on ethnic background [15]. All these prompted us to perform the present study to examine the association of serum osteocalcin level with MetS in a Chinese male population.

Section snippets

Study population

The Fangchenggang Area Male Health and Examination Survey was a population-based study conducted among noninstitutionalized Chinese men aging from 17 to 88 years old in Guangxi, which was designed to investigate the effects of environmental and genetic factors and their interaction with the development of age-related chronic diseases. A comprehensive demographic and health survey was conducted among 4303 continuous men who participated in a large-scale physical examination in the Medical Centre

Results

The characteristics of the participants were shown in Table 1. Data were presented for participants divided into MetS (n = 297) and non-MetS (n = 2047). Among all individuals, the prevalence of MetS was 12.7%. Compared with participants with non-MetS, men with MetS had lower serum osteocalcin levels (−3.76, P < .001) (Table 1).

The mean concentration of serum osteocalcin was 23.57 ng/mL in the study population, with a standard deviation of 1.38 ng/mL. A trend of decreased osteocalcin associated

Discussion

This is the first large cross-sectional study to highlight the important relationship between osteocalcin levels and MetS in a Chinese male population. Consistent with the previous study[19], osteocalcin levels decreased with age. The prevalence of MetS (12.7%) in Fangchenggang area of Guangxi was similar to the prevalence of MetS in China in 2000-2001 (13.6%) based on the modified Adult Treatment Panel III criteria [7].

Our study revealed that serum osteocalcin levels were significantly

Acknowledgment

The work described in this article is supported by grants from Guangxi Graduate Education Innovation Program (2010105981002M175), the National Natural Science Foundation of China (30945204, 81060029) and the Guangxi Provincial Department of Finance and Education (2009GJCJ150). We express our sincere thanks to the local research teams from Fangchenggang First People's Hospital, Fangchenggang, China, for their contribution to the survey.

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    Author contribution statement: AT, YG, XY, HZ, NX, and ZM designed the study. LM, AT, and YG collected samples and conducted the osteocalcin measurement. XQ and TP supervised the laboratory work. XY and HZ conducted the statistical analyses. AT wrote the first draft of the paper. NX, YG, and ZM revised the manuscript for important intellectual content.

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