metabolic syndrome ( mets ) is a clustering of metabolic risk factors for atherosclerotic cardiovascular disease and diabetes mellitus ( dm ) . there are more than 415 million people affected by dm worldwide and it is one of the most important public health challenges of the twenty - first century . adipocyte fatty acid binding protein ( a - fabp ) is one of the most abundant proteins in mature adipocytes , which is known for the ability to bind fatty acids and related compounds throughout various cellular compartments , including the peroxisomes , mitochondria , endoplasmic reticulum , lipid droplets , and nucleus [ 3 , 4 ] . a - fabp has been shown to affect insulin sensitivity , lipid metabolism , and lipolysis in animal studies . furthermore , studies also found that a - fabp is a key mediator for the obesity - related cardiovascular disease and is positively associated with mets [ 3 , 5 ] . our previous studies noted that a - fabp was associated with mets in coronary artery disease and in hemodialysis patients [ 6 , 7 ] . the aim of this study was to investigate the relationship between fasting serum a - fabp level and the mets among type 2 dm patients . there were 165 type 2 dm patients enrolled from a medical center in hualien , taiwan , from november 2014 through march 2015 . the protection of the human subjects institutional review board of tzu chi university and hospital approved this study . blood pressure ( bp ) was measured by trained staff in the morning using standard mercury sphygmomanometers with appropriate cuff sizes after sitting for at least 10 minutes . systolic bp ( sbp ) and diastolic bp ( dbp ) were taken 3 times at 5  min intervals and were averaged for analysis . patients who were diagnosed with hypertension were defined as sbp  140  mmhg and/or dbp  90  mmhg or have received any antihypertensive medication in the past 2 weeks . patients were excluded if they had an acute infection , acute myocardial infarction , heart failure , and malignancy at the time of blood sampling , or if they refused to provide informed consent for the study . body weight of participant was measured in light clothing and without shoes to the nearest 0.5 kilograms , and body height was measured to the nearest 0.5  cm . waist circumference was measured using a tape measurement around the waist from the point between the lowest ribs and the hip bones with the hands on the hips . body mass index ( bmi ) was calculated as the weight in kilograms divided by the height in meters squared . bioimpedance measurements of fat mass were performed at the bedside according to the standard tetrapolar whole body ( hand - foot ) technique , using a single - frequency ( 50  khz ) analyzer ( biodynamic-450 , biodynamics corporation , seattle , usa ) . fasting blood samples ( approximately 5  ml ) of all participants were immediately centrifuged at 3000  g for 10  min . serum levels of albumin , blood urea nitrogen ( bun ) , creatinine , fasting glucose , glycated hemoglobin ( hba1c ) , total cholesterol ( tch ) , triglycerides ( tg ) , high - density lipoprotein cholesterol ( hdl - c ) , low - density lipoprotein cholesterol ( ldl - c ) , and high - sensitivity c - reactive protein ( hs - crp ) were measured using an autoanalyzer ( siemens advia 1800 , siemens healthcare gmbh , henkestr , germany ) [ 68 ] . serum a - fabp levels were measured using a commercially available enzyme immunoassay ( eia ; spi - bio , montigny le bretonneux , france ) [ 68 ] . serum insulin levels were measured using the commercially available enzyme - linked immunosorbent assay ( elisa ) ( labor diagnostika nord , nordhorn , germany ) [ 9 , 10 ] . insulin resistance was evaluated using a homeostasis model assessment of insulin resistance ( homa - ir ) as follows : homa - ir = fasting plasma glucose ( mg / dl )  fasting serum insulin ( u / ml)/405 [ 9 , 10 ] . the estimate glomerular filtration rate ( gfr ) was calculated using the modification of diet in renal disease ( mdrd ) study equation in this study . people were classified as having mets if they had central ( abdominal ) obesity with a waist circumference  90  cm ( men ) or 80  cm ( women ) ( chinese criteria ) and matched two or more of the following criteria : fasting serum glucose  110  mg / dl , triglycerides  150  mg / dl , hdl - c level < 40  mg / dl in men or < 50  mg / dl in women , or blood pressure  130/85  mmhg . the use of antihypertensive drug was considered as indicative of high blood pressure in this analysis . a patient was considered dm patient if the fasting plasma glucose was 126  mg / dl , or if antidiabetic therapy was used [ 68 ] . normally distributed data are expressed as the mean  standard deviation ( sd ) and comparisons between patients were performed using student 's independent t - test ( two - tailed ) . data are not normally distributed are expressed as medians and interquartile ranges and comparisons between patients were performed using the mann whitney u test ( age , tg , fasting glucose , hba1c , bun , creatinine , hs - crp , insulin , and homa - ir ) . data expressed as the number of patients were analyzed by  test , because age , tg , fasting glucose , hba1c , bun , creatinine , hs - crp , insulin , and homa - ir were not normally distributed and underwent base 10 logarithmic transformations to achieve normality . clinical variables that correlated with serum a - fabp levels in dm patients were evaluated using univariate linear regression analysis . variables that were significantly associated with a - fabp levels in dm patients were tested for independency in multivariate forward stepwise regression analysis . data were analyzed using spss for windows ( version 19.0 ; spss inc . , chicago , il , usa ) . one hundred thirteen dm persons ( 68.5% ) had mets , and 52 dm persons ( 31.5% ) did not . diabetic persons who had mets had significantly higher serum fasting a - fabp levels than those without mets ( p < 0.001 ) . compared with dm patients without mets , those with mets showed a much higher proportion of females ( p = 0.002 ) and as expected more hypertension ( p = 0.001 ) , higher waist circumference ( p < 0.001 ) , body weight ( p < 0.001 ) , and bmi ( p < 0.001 ) , higher fasting glucoses ( p = 0.033 ) , tg ( p = 0.001 ) , and lower hdl - c concentrations ( p < 0.001 ) since mets represents a constellation of hypertension , abdominal obesity , impaired fasting glucose , and dyslipidemia . moreover , dm patients with mets had higher body fat mass ( p < 0.001 ) , hba1c level ( p = 0.007 ) , bun ( p = 0.020 ) , hs - crp ( p < 0.001 ) , insulin level ( p < 0.001 ) , homa - ir ( p < 0.001 ) , and lower gfr ( p = 0.021 ) . clinical characteristics and serum a - fabp values for the 165 dm patients are presented in table 2 . a - fabp level was statistically significantly higher in female dm persons than male dm persons ( p < 0.001 ) . no statistically significant differences in a - fabp levels were found as a function of smoking ; presence of hypertension ; or use of statin , fibrate , or antidiabetic drugs . univariate linear analysis of clinical variables associated with fasting serum a - fabp levels in dm patients is presented in table 3 . height ( r = 0.293 ; p < 0.001 ) and serum albumin level ( r = 0.259 ; p = 0.001 ) were negatively correlated , while bmi ( r = 0.173 ; p = 0.026 ) , body fat mass ( r = 0.394 ; p < 0.001 ) , sbp ( r = 0.324 ; p < 0.001 ) , dbp ( r = 0.173 ; p = 0.026 ) , tch ( r = 0.179 ; p = 0.022 ) , and logarithmically transformed tg ( log - tg , r = 0.227 ; p = 0.003 ) were positively correlated with serum a - fabp levels in type 2 dm patients . furthermore , log - hba1c ( r = 0.225 ; p = 0.004 ) , log - bun ( r = 0.363 ; p < 0.001 ) , log - creatinine ( r = 0.257 ; p = 0.001 ) , log - hs - crp ( r = 0.212 ; p = 0.006 ) , log - insulin ( r = 0.214 ; p = 0.006 ) , and log - homa - ir ( r = 0.218 ; p = 0.005 ) were positively correlated , while gfr ( r = 0.343 ; p < 0.001 ) was negatively correlated with serum a - fabp levels in this study . multivariate forward stepwise linear regression analysis of the variables significantly associated with fasting serum a - fabp levels revealed that body fat mass ( adjusted r change = 0.150 ; p < 0.001 ) , log - creatinine ( adjusted r change = 0.140 ; p < 0.001 ) , female dm patients ( adjusted r change = 0.051 ; p < 0.001 ) , serum albumin level ( adjusted r change = 0.029 ; p = 0.004 ) , log - hs - crp ( adjusted r change = 0.020 ; p = 0.013 ) , and gfr ( adjusted r change = 0.012 ; p = 0.043 ) were independent predictors of these values for type 2 dm patients ( table 4 ) . our study showed that fasting a - fabp levels were higher in type 2 dm patents with mets , and body fat mass , creatinine , female , albumin , hs - crp , and gfr were independent predictors of serum a - fabp levels in type 2 dm patients . mets is defined by the presence of central obesity , hyperglycemia , type 2 dm , hypertension , and dyslipidemia . the prevalence of mets was 46.9% for males and 65.1% for females in type 2 dm patients in a korean study   and 78.6% in type 2 dm patients in brazil . in this study , patients with type 2 dm and mets showed significantly higher blood crp and insulin resistance than type 2 dm without mets . our study noted that diabetic persons who had mets had significantly higher in - body fat mass , hba1c level , hs - crp , insulin level , and homa - ir than those diabetic persons without mets . females are at greater risk of obesity and central adiposity due to their increased propensity to gain fat . our results found that diabetic persons who had mets had higher trend in female gender . mets and its components are associated with the development of chronic kidney disease and microalbuminuria or overt proteinuria . our study also noted that mets in patients with type 2 dm had higher serum bun level and lower gfr . studies in a - fabp knockout mice and a - fabp inhibitor treated animals suggest that a - fabp has an important role in lipolysis and regulating insulin sensitivity [ 3 , 5 , 17 , 18 ] . recent studies also demonstrated a - fabp expression in macrophages and modulate inflammatory responses and cholesterol ester accumulation [ 3 , 5 , 19 ] . all of these results indicate that a - fabp has an important role in the development of major components of the mets through its distinct actions in adipocytes and macrophages . serum a - fabp levels predict the development of the mets in a chinese and a korean cohort study [ 20 , 21 ] and plasma a - fabp level was found to be a strong predictor of type 2 dm independently of the traditional risk factors including obesity , insulin resistance , or glycemic indexes . cabr et al . noted a - fabp levels positively correlated to the mets in type 2 dm subjects . our study also noted higher serum a - fabp level in type 2 dm patients who had mets . our study also noted that female diabetic patients had higher a - fabp levels than man . in type 2 dm patients , a - fabp levels were positively correlated with bmi , tg , tch , sbp , waist circumference , il-6 , tnf- , and hs - crp [ 23 , 25 ] . furthermore , a - fabp levels were positively correlated with plasma tg , apolipoprotein c - iii , and all the components of tg - rich lipoproteins in type 2 diabetic subjects . a - fabp levels positively correlated with bmi , glucose , insulin levels , homa - ir , and crp in morbidly obese women . subjects in the highest a - fabp tertile at baseline exhibited higher values for bmi , body fat mass , blood pressure , fasting glucose , tch , tg , ldl - c , insulin , and homa - ir in a total of 465 participants in a korean study . a - fabp was independently associated with body fat mass in a cohort of chinese women without dm . serum a - fabp concentrations were positively associated with serum creatinine and albumin and predict a worse hospital outcome in critically ill patients with sepsis . since studies also noted serum a - fabp4 levels correlated positively with serum creatinine and negatively with gfr in type 2 dm patients [ 30 , 31 ] . serum a - fabp level was independently associated with macrovascular complications in type 2 dm patients . we also noted that bmi , body fat mass , sbp , dbp , tch , log - tg , log - creatinine , log - hba1c , log - hs - crp , log - insulin , and log - homa - ir were positively correlated with a - fabp levels , while height , albumin , and gfr were negatively correlated with a - fabp levels in our dm subjects . after adjustment for a variety of confounders in multivariable forward stepwise linear regression analysis , body fat mass , log - creatinine , female dm patients , and log - hs - crp remained to be positively associated , while serum albumin level and gfr negatively associated with a - fabp level . first , this study had a cross - sectional design without a control group with a limited number of participants enrolled and the possibility of bias can not be excluded . second , pharmacological interventions have been shown to influence serum a - fabp in humans . our patients did not use any the sodium / glucose cotransporter 2 ( sglt2 ) inhibitor . our results did not show a relationship between thiazolidinedione , stains , fibrates or other antidiabetic drugs , and serum a - fabp in the diabetic patients studied . further studies are required to elucidate the relationship between medication and a - fabp in type 2 dm patients . in summary , the present study showed that serum a - fabp level was positively associated with mets in the type 2 dm patients . in addition , body fat mass , log - creatinine , female dm patients , and log - hs - crp are positively correlated , while serum albumin and gfr are negatively correlated with a - fabp level .
adipocyte fatty acid binding protein ( a - fabp ) is a key mediator of obesity - related metabolic syndrome ( mets ) . 
 the aim of this study was to evaluate the relationship between a - fabp concentration and mets in type 2 diabetes mellitus ( dm ) patients . 
 fasting blood samples were obtained from 165 type 2 dm volunteers . 
 mets and its components were defined using diagnostic criteria from the international diabetes federation . among 165 dm patients , 113 patients ( 68.5% ) had mets . 
 diabetic persons who had mets had significantly higher a - fabp levels ( p < 0.001 ) than those without mets . 
 female dm persons had higher a - fabp level than man ( p < 0.001 ) . 
 no statistically significant differences in a - fabp levels were found in use of statin , fibrate , or antidiabetic drugs . 
 multivariate forward stepwise linear regression analysis revealed that body fat mass ( p < 0.001 ) , logarithmically transformed creatinine ( log - creatinine ; p < 0.001 ) , female dm patients ( p < 0.001 ) , and logarithmically transformed high sensitive c - reactive protein ( log - hs - crp ; p = 0.013 ) were positively correlated , while albumin ( p = 0.004 ) and glomerular filtration rate ( gfr ; p = 0.043 ) were negatively correlated with serum a - fabp levels in type 2 dm patients . in this study , 
 higher serum a - fabp level was positively associated with mets in type 2 dm patients .