Abstract： Objective To explore the diagnostic significance of homeostasis model assessment of insulin resistance (HOMA IR)in metabolic syndrome among subjects with different glucose tolerance Methods Given 75g oral glucose tolerance test, 15,568 Chinese were divided into normal glucose tolerance(NGT) group, impaired glucose regulation(IGR) group, diabetes mellitus group Metabolic syndrome (MS) was diagnosed according to the definition proposed by WHO in 1999 Results (1) The cutoff point(2 69) of insulin resistance was defined as a HOMA IR exceeding the 75th percentile of the distribution in 10 147 NGT subjects aged 25～74 years The prevalence of the MS, IGR, DM and insulin resistance were 59 0%,19 58%, 25 28% and 29 22%(standardized to the 2000 Chinese population), respectively The distribution frequency of insulin resistance was 45 30% in MS subgroup of IGR+DM group (3) Logistic regression analysis demonstrated that waist hip ratio and blood pressure were significantly positively correlated with development of MS in NGT group, IGR+DM group, and general group But, HOMA IR was significantly positively correlated with development of MS in NGT group The predictable concordance on development of MS was 0 90 in every analysis model ( P =0 0001) Conclusions HOMA IR as a diagnostic index of MS is not suitable for all persons It is not sensitive in patients with hyperglycemia It is, however, a simple, accurate parameter for the diagnosis of MS in subjects with NGT In those patients with hyperglycemia, the diagnosis of insulin resistance depends on a variety of parameters