Association Between Serum 25-(OH)D Concentrations And Metabolic Syndrome In The Middle-aged And Elderly Chinese Population

Background:Metabolic syndrome(MetS)is a cluster of interconnected metabolic abnormalities and cardiovascular risk factors,which associated with increased risk of type 2 diabetes mellitus as well as cardiovascular disease and has become an increasing public health problem because of rapid lifestyle changes.Vitamin D insufficiency is known to be caused by decreased bio-availability secondary to the deposition of vitamin D in body fat compartments.Appropriately Vitamin D status is increasingly linked to the development of the impact factors associated with MetS to play a role in containing the glycemic and atherogenic profiles.However,serum 25-hydroxyvitamin D[(25-(OH)D]levels have been associated with MetS but the data are inconsistent and no studies have addressed these inter-relationships in the Dalian Port hospital so far where the association of these conditions is high.Thus,Serum vitamin D level is able to predict the long-term risk of cardiovascular disease or may have protective effects against the development of MetS in the entire population.This study was aimed to investigate the correlation between serum 25-(OH)D concentrations and MetS in the middle-aged and elderly Chinese population.Methods:A community-based comparative cross-sectional study based on the Prospective Cohort Study of Relative Factors of Heart Failure among Elderly People(PCSRFHFEP)was carried out in 2764 participants.The joint interim statement of American Association of Clinical Endocrinologists(AACE)was used for the standard definition of MetS.Serum 25-(OH)D concentrations were measured by electro-chemiluminescence immunoassay(ECLIA).Data is presented as means ± standard deviation(SD)for all continuous variables,whereas counts and percentiles were used for categorical variables.Participants with MetS and non-MetS were compared by inter-quartile range or proportion of major MetS risk factors,by using the Mann-Whitney-U test for non-normally distributed data and chi-square(?2)test for proportion.Also,subjects were categorized into quartile s based on serum 25-(OH)D concentrations and the quartiles were calculated for the differences using ANOVA and chi-square test for continuous and categorical data,respectively.A logistic regression analysis model was applied to estimate the odds ratios(ORs)and 95%CIs for each quartile of serum 25-(OH)D concentrations compared to the highest quartile.The multivariable model was adjusted for gender,age,total cholesterol,low-density lipoprotein,creatinine,cigarette status,alcohol consumption,and physical activity,whereas model 1 was unadjusted.Multi-collinearity was assessed for the explanatory variables using tolerances and the variance inflation factors(VIF).The VIF of total cholesterol was greater than 10,indicating that there were high correlations among the independent(predictor)variables.Results:Serum 25-(OH)D levels were markedly lower in the MetS group than in those without MetS in men.There was an inverse association between serum 25-(OH)D and gender(?=-0.266,95%CI=-5.278?-3.118;P<0.001),and triglycerides((?=-0.058,95%CI=-0.669?-0.120;P=0.005).However,the association between serum 25-(OH)D and gender showed that there was a need for gender-based analysis when looking at the predictive power of serum 25-(OH)D levels and the presence of MetS.The prevalence of MetS in the middle and elderly aged Chinese was 12.61%,in which the prevalence of MetS in men was slightly higher than that of women(13.97%versus 11.65%).Meanwhile,the prevalence of MetS among current alcohol users was 13.9%,while current smokers were linked to a lower prevalence of MetS(12.6%).In spite of that,Participants with both smokers and alcohol users were remarkable in MetS compared to the non-MetS group.Participants diagnosed with diabetes mellitus were also with the remarkable prevalence of MetS(43%).The median values of systolic blood pressure,diastolic blood pressure,triglycerides,high-density lipoprotein,and low-density lipoprotein were significantly higher in the MetS group compared to non-MetS(p<0.01).However,the median values of creatinine and total cholesterol were not statistically different between the Mets and non-MetS group.We observed a negative correlation between the higher quartiles of serum 25-(OH)D levels and the presence of MetS among men.Compared with subjects in the first quartile,the positive and persistent correlations were observed between the higher quartiles of serum 25-(OH)D levels and MetS in the entire population with only adjusted for potential confounders.The correlation between serum 25-(OH)D levels and the prevalence of MetS in men persisted even after adjusting for potential confounders including,age,cigarette status,alcohol use,physical activity,low-density lipoprotein,creatinine,and total serum cholesterol.An adjusted ORs and 95%CI of MetS in the second through fourth compared with the lowest quartile for serum 25-(OH)D levels were 0.93(0.54-1.59),0.89(0.50-1.56),and 0.48(0.28-0.84),respectively.Conclusions:In conclusion,our study found decreased serum 25-(OH)D level was significantly correlated to MetS in the middle-aged men,or higher circulating serum vitamin D is linked to a decreased likelihood of having MetS among Chinese middle-aged men.Therefore,serum 25-(OH)D could be used as a potential bio-marker in the prevention and management of MetS.