polycystic ovary syndrome ( pcos ) is one of the most common endocrine disorders , affecting around 47% of reproductive - aged women . the etiology of pcos remains to be elucidated , although insulin resistance ( ir ) and hyperinsulinemia seem to be the important mechanism for pcos and its metabolic derangements     [ 2 , 3 ] , diabetes mellitus ( dm ) in particular     [ 4 , 5 ] . it has been reported that pcos women are at high risk of ir as shown by various markers , for example , impaired glucose tolerance of 2531% , and type 2 dm of 7.510%     [ 6 , 7 ] . patients with ir , especially those with dm , have a high risk for developing cardiovascular disease in the future     [ 8 , 9 ] . although pcos women have a high risk of ir , the rotterdam eshre / asrm - sponsored pcos consensus workshop group does not recommend any test of ir to be routinely used in clinical practice . however , it is suggested that in large - scale clinical or epidemiological studies , simple methods such as fasting plasma glucose ( fpg ) and oral glucose tolerance test ( ogtt ) may provide effective estimates for ir .   in our previous report , we found that the pcos women at our clinic were relatively young and thin as compared with those in other reports     [ 6 , 7 , 12 ] . the objectives of the present study were to investigate the prevalence and clinical predictors of ir in pcos thai women . the present cross - sectional study was conducted at the gynecologic endocrinology unit , faculty of medicine siriraj hospital , mahidol university . participants were all pcos thai women who registered to the siriraj pcos project from may 2007 to january 2009 . additional exclusion criteria were women who had previous surgery of one or both ovaries , used hormonal treatment , took the medication for dyslipidemia within 3 months , or took steroid within 6 months before registering to the project .   after a written informed consent was obtained , a structured medical record form was used to collect the following data : clinical presentation , medical history , age , body weight , height , waist circumference ( wc ) , blood pressure , and skin manifestations . the first sample was drawn at 810 am after overnight fasting for at least 12 hours , and the second samples was drawn two hours after 75  g oral glucose loading . the first blood sample was examined for baseline metabolic profiles ( fasting blood glucose ( fbg ) , cholesterol , triglyceride , high density lipoprotein cholesterol ( hdl - c ) , low density lipoprotein cholesterol ( ldl - c ) ) , and hormonal profiles ( total testosterone , prolactin , thyroid stimulating hormone ( tsh ) , and cortisol ) . obesity was defined as body mass index ( bmi ) 25  kg / m according to the who cutoff points for asian populations . central obesity was defined as wc 80  cm   according to the international diabetes federation ( idf ) 2005 . acanthosis nigricans was a cutaneous condition characterized by a velvety darkening of the skin in the posterior region of neck , axillae , antecubital fossa , groin , and other areas . hypertension was defined as systolic blood pressure of 140  mmhg or diastolic blood pressure of 90  mmhg , according to the world health organization / international society of hypertension writing group ( who / ish ) 2003 . dyslipidemia was defined as cholesterol 200  mg / dl , ldl - c 160  mg / dl , hdl - c < 50  mg / dl , or triglyceride 150  mg / dl , according to national cholesterol education program adult treatment panel ( ncep atp ) iii . clinical hyperandrogenism was considered if the participants had at least one of the followings : hirsutism ( a modified ferriman - gallwey score 8 ) , acne , androgenic alopecia , or virilization . hyperandrogenemia was defined as total testosterone > 0.8  ng / dl ,   free testosterone > 0.006  ng / dl , or dehydroepiandrosterone sulphate ( dheas ) > 350  mcg / dl . abnormal plasma ogtt was classified according to the american diabetes association ( ada ) 2003 criteria   as follows : ( i ) impaired fasting glucose ( ifg ) , that is , fasting blood glucose ( fbg ) 100 and < 126  mg / dl , ( ii ) impaired glucose tolerance test ( igt ) , that is , 2-hr glucose 140 and < 200  mg / dl , and ( iii ) type 2 dm , that is , fbg 126  mg / dl or 2-hr glucose 200  mg / dl . in the present study , ir was defined as the presence of ifg , igt , or type 2 dm . all laboratory assays were performed at the laboratory unit of the department of clinical pathology , faculty of medicine siriraj hospital , mahidol university , the central laboratory certified by is0 15189 . all assays were done using automatic analyzers , modular p800 , roche ( for total cholesterol , hdl - c , ldl - c , triglycerides , glucose , and albumin ) and modular e170 , roche ( for insulin , tsh , prolactin , cortisol , total testosterone , and dheas ) . serum - free testosterone was calculated from serum total testosterone , sex hormone - binding globulin ( shbg ) and albumin using the online computer program of international society for the study of the aging male ( issam ) . all techniques had intra- and interassay coefficients of variation ( cv ) less than 5% . when an estimated prevalence of ir = 20% ( from our pilot study ) , precision error of estimation ( 25% of p ) = 0.05 , and  = 0.05 , a sample size of at least 246 was needed . the normality of distribution of all continuous variables was checked using kolmogorov - smirnov test . data were presented in mean and standard deviation ( sd ) , number ( n ) and percent ( % ) , or odds ratio ( or ) and 95% confidence interval ( ci ) , as appropriate . univariate analysis using student t - test , mann - whitney u test ( for continuous data ) , or chi - square test or fisher 's exact test ( for categorical data ) was applied to survey potential predictors of ir . all tests were two - sided , and statistical significance was considered to exist when a p value was < 0.05 . table 1 demonstrates clinical and laboratory characteristics of 250 reproductive - aged thai women with pcos . the mean  sd of age , body mass index ( bmi ) , and waist circumference ( wc ) were 25.4  5.8 years , 26.2  7.6  kg / m , and 82.3  16.3  cm , respectively . almost all of the participants ( 98.4% ) presented with oligomenorrhea . of all participants , the overall prevalence was 20.0% which included 3.2% of ifg , 13.6% of igt , and 5.6% of type 2 dm ( 3.6% of fbs 126  mg / dl , 5.2% of 2-hr glucose 200  mg / dl , and 3.2% of combined abnormalities ) . table 3 shows clinical predictors for ir in 250 pcos thai women . comparing with the patients without ir , the ones with ir were older , and had a higher bmi , larger wc , and higher prevalence of hypertension , acanthosis nigricans , and dyslipidemia . the results from multiple logistic regression analysis by forward stepwise technique showed that the independent predictors for ir included age of 30 years old , wc of 80  cm , presence of an , and dyslipidemia , with odds ratios of 2.14 ( 95% ci 1.014.52 ) , 3.53 ( 95% ci 1.289.75 ) , 2.63 ( 95% ci 1.175.88 ) , and 3.07 ( 95% ci 1.168.11 ) , respectively . insulin resistance is a metabolic disorder caused by the impairment of insulin function in inducing glucose uptake and utilization . in clinical setting , these techniques , including fpg , ogtt , glucose / insulin ratio , homeostasis model assessment for insulin resistance ( homa - ir ) , and quantitative insulin sensitivity check index ( quicki ) , are shown to correlate well with the gold standard , that is , euglycemic - hyperinsulinemic clamp     [ 22 , 23 ] . to date , it is still inconclusive to judge the superiority of one technique over the others     [ 24 , 25 ] . in the present study , we used fpg and ogtt as suggested by the rotterdam eshre / asrm - sponsored pcos consensus workshop group . interestingly 88.2% ( 30/34 ) of the patients with igt and 85.7% ( 12/14 ) of those with type 2 dm did not have ifg . our finding was in line with the previous information that fpg alone is not a sensitive indicator for ir in women with pcos     [ 6 , 7 , 26 ] . the prevalence of ir in our pcos women was lower than that of many reports     [ 6 , 7 , 27 ] which revealed the prevalence up to 75% . the difference in techniques used to define ir was responsible for such large discrepancy . however , even using similar definition , the prevalence of ir in our study was still lower than that in other studies     [ 6 , 28 , 29 ] . this was owing to the fact of that our study population was relatively young and thin . previous studies showed that the prevalence of ir increased with age and bmi     [ 6 , 7 ] .   in the present relatively young and thin pcos women , many factors associating with ir were similar to those with metabolic syndrome     [ 17 , 30 ] as these two conditions are closely related     [ 31 , 32 ] . these factors included age , central obesity , presence of acanthosis nigricans , and dyslipidemia . hypertension and high bmi were shown to be associated with ir in univariate analysis but regression analysis indicated that these two variables were not independent factors . moreover , the association between ir and central obesity but not bmi suggested the effect of body fat distribution on insulin metabolism . previous studies showed that android fat distribution and upper - half type body fat distribution were linked to insulin resistance in pcos     [ 3335 ] . hyperandrogenemia , a diagnostic criterion for pcos , was shown to be significantly associated with ir in our univariate analysis . the discrepancy result between these two analyses indicated that hyperandrogenemia had less impact on ir than other factors did . the association between hyperandrogenemia and ir was also demonstrated in previous reports     [ 38 , 39 ] . the pathophysiology of pcos comprising a model of complex interaction between hyperandrogenemia and ir is well accepted . however , the results of some studies suggested that these two conditions might be two separate entities     [ 38 , 41 ] . the absence of significant association between hyperandrogenemia and ir in the present study might confirm the concept of two separate entities . however , we could not disregard the important of ethnicity on this issue . to date the reference values used in the present study derived from the us population , the values of which might not be applicable for our population . due to the limitation of a cross - sectional study , the prevalence of ir found at the initial visit would change with time . therefore , a long - term prospective study is needed to reveal the actual prevalence in our population , and the effect of metabolic derangement on future health status . furthermore , the majority of our participants were urbanized women ; therefore , they might not represent the whole picture of pcos thai women . the overall prevalence of abnormal ogtt in reproductive - aged thai women with pcos is 20.0% . clinical predictors are age of 30 years , central obesity , presence of acanthosis nigricans , and dyslipidemia , but not hyperandrogenemia . it is probably beneficial to screen for ir in these specific groups of pcos women in order to provide optimum management for each patient .
objectives . to determine the prevalence of insulin resistance ( ir ) and its predictors in reproductive - aged thai women with polycystic ovary syndrome ( pcos ) . methods . 
 a cross - sectional study was conducted from may 2007 to january 2009 . 
 participants were 250  thai women with pcos . 
 information regarding medical history and physical examination and results of 75 gram ogtt were recorded . 
 results . 
 the overall prevalence of ir was 20.0% , comprising the prevalence of impaired fasting glucose , impaired glucose tolerance , and diabetic mellitus of 3.2% , 13.6% , and 5.6% , respectively . 
 multiple logistic regression analysis showed that the independent predictors for ir were age of 30 years old , waist circumference ( wc ) of 80  cm , presence of acanthosis nigricans ( an ) , and dyslipidemia with odds ratios ( 95% confidence interval ) of 2.14 ( 1.014.52 ) , 3.53 ( 1.289.75 ) , 2.63 ( 1.175.88 ) , and 3.07 ( 1.168.11 ) , respectively . 
 conclusion . 
 the overall prevalence of ir in reproductive - aged thai women with pcos is 20.0% . 
 age 30 years old , wc 80  cm , the presence of an , and dyslipidemia are the significant clinical predictors .