The Associations Of Body Fat,Muscle Mass With Metabolic Syndrome And Their Risk Of Long-term Events

Backgrounds and ObjectivesMetabolic syndrome(MetS)is a cluster of metabolic risk factors including central obesity,insulin resistance,hypertension,and dyslipidemia.MetS increases the risk of type 2 diabetes and cardiovascular diseases.Obesity,especially central obesity,is one of the most important risk factors for MetS.Due to their own limitations,the indices like BMI,waist circumference and waist-to-hip ratio lack efficiency in identifying individuals at risk.The core of metabolic syndrome is insulin resistance.Skeletal muscle is the main site of insulin-mediated glucose metabolism,and it's also an important endocrine organ of the human body.In addition to acting on itself in an autocrine/paracrine manner,it can also participate in regulating the energy metabolism of the body through long-distance secretion,thereby affecting the metabolic state of the body.Researchers have found that mice injected with recombinant myostatin-a cytokine secreted by skeletal muscle that inhibits myocyte growth-developed insulin resistance.To date,there are just a few studies focusing on the association of skeletal muscle content with MetS in homo sapiens,of which many studies focused on the phenotypes of "sarcopenia",and few studies have focused on the interaction between body fat and skeletal muscle.This study aims to explore the relationship between body composition and MetS as well as metabolic risk factors,and the interaction between body fat and skeletal muscle.Then,we evaluate the risk of type 2 diabetes,coronary heart disease and stroke in subjects of different phenotypes in a cohort.Materials and MethodsThe study was divided into two parts.Data for cross-sectional study was collected in an epidemiology survey of Metabolic syndrome in 2014,which included questionnaires,biochemical tests and physical examinations.Measurement of body composition was performed using an Inbody 720 body composition analyzer.After excluding subjects with diabetes,cardiovascular diseases at baseline,we used the disease surveillance system and the medical insurance system to collect the data of subjects who developed diseases of type 2 diabetes,coronary heart disease and stroke since baseline.After data were collected,Pearson correlation analysis was used to study the correlation of skeletal muscle and body fat with height and weight.We used present skeletal muscle mass(%SM),percent bosy fat(%BF)and visceral fat area(VFA)to measure akeletal muscle mass and bofy fat.Unconditional logistic regression analysis was used to assess the relationship between%BF,VFA,%SM,SM/BF,SM/VFA and MetS as well as metabolic risk factors.The interactions between%SM and%BF,%SM and VFA were analyzed.In the cohort study,the subjects were divided into low%SM group and high%SM group according to sex-specific means of%SM at baseline,when in%BF's case,the sex-specific means of%BF were used instead,and so was VFA.With low%SM group as reference group,Cox proportional hazard regression model was used to calculate the HR and 95%CI of long-terms events in high%SM group.All statistical analyses were performed using SPSS 22.0.Results1.Both in male and female,total skeletal muscle mass were negatively correlated with age,while VFA was positively correlated with age,and total fat mass and age were not significantly correlated(total skeletal muscle mass:male:r=-0.273,P<0.001,female:r=-0.131,P=0.015;VFA:male:r=0.138,P=0.015,female:r=0.348,P<0.001).Total skeletal muscle mass was positively correlated with height and weight(height:male:r=0.686,P<0.001,female:r=0.633,P<0.001;weight:male:r=0.831,P<0.001;female:r=0.799,P<0.001).Total fat mass was positively correlated with body weight(male:r=0.800,P<0.001,female:r=0.906,P<0.001).After adjusting for body weight,total skeletal muscle mass was negatively correlated with total fat mass(male:r=-0.994,P<0.001,female:r=-0.994,P<0.001).2.After adjusting for age,high%SM,low%BF,low VFA,high SM/BF and Sm/VFA significantly reduced the risk of MetS and each of five metabolic risk factors(P<0.05).After adjusting for age,and BMI,high%SM reduced the risk of MetS and TG,HDL-C,and FPG abnormalities.High%BF increases the risk of MetS and TG,FPG abnormalities.High VFA increased the risk of MetS,TG and FPG abnormalities.High SM/BF reduced the risk of MetS and TG abnormalities(P<0.05).There was no significant association between%SM,%BF,VFA SM/BF,SM/VFA and other metabolic risk factors.3.%SM,%BF,VFA,SM/BF and SM/VFA all had a good assessment of the risk of MetS,among which VFA is optimal(male:AUC=0.818,female:AUC=0.803),SM/BF and SM/VFA had not been found to have better assessment than%SM,%BF and VFA.4.The interaction of%BF and%SM were found in FPG abnormalities(P=0.013).Among subjects with low%BF,there was no significant difference in the prevalence of FPG abnormalities in high%SM and low%SM groups.Compared with individuals of low%BF/high%SM,the individuals of high%BF/low%SM had a 1.60-fold risk of FPG abnormalities.5.The association between%SM,%BF,VFA and long-term events were not observed in this study.ConclusionIn this study,we analyzed the characteristics of body fat mass and skeletal muscle mass of 655 subjects,and assessed the relationship of%BF,%SM with MetS as well as metabolic risk factors.Then,we evaluated the risk of type 2 diabetes,coronary heart disease and stroke in subjects of different phenotypes in a cohort.The results showed that individuals with low%SM,high%BF and high VFA might be more susceptible to MetS and TG,FPG abnormalities,and the interaction between%BF and%SM was found in FPG abnormalities.