Objective To compare urinary microalbumin levels and prevalence of microalbuminuria in subjects with normal glucose tolerance (NGT) and prediabetes including various types of impaired glucose regulation. Methods During 2007-2008, subjects (n=47 325), aged ≥20 years, including 18 976 males and 28 349 females, from 152 city blocks and 112 villages in China, were recruited using stratified and multi-staged sampling methods. According to the results of 75 g oral glucose tolerance test (OGTT), participants were divided to NGT group, isolated impaired fasting glucose (i-IFG) group, isolated impaired glucose tolerance (i-IGT) and impaired fasting glucose with impaired glucose tolerance group (IGT/IFG). Abnormal urinary microalbumin was defined if its level was above 30 mg/L. The urinary microalbumin levels and the prevalence of abnormal microalbuminuria were compared and analyzed among groups. Analysis of variance, rank sum test and multiple linear regression were applied for statistical analysis. Results The urinary microalbumin level [media (upper-lower quantiles)] in IGT/IFG group was 16(8~37) mg/L and that in i-IGT group was 13(7-30) mg/L. Both were higher than that in NGT group [10(6-21) mg/L](all P<0.01);but there was no significant difference between NGT group and i-IFG group [11(6-24) mg/L]. The prevalence of abnormal urinary microalbumin was 31.5% in IGT/IFG group, 25.0% in i-IGT group, 20.2% in i-IFG group and 17.6% in NGT group. Conclusion The prevalence of abnormal microalbuminuria is already increased even at the pre-diabetic stage. That suggests we should manage risk factors for microalbuminuria of these patients as early as possible. [ABSTRACT FROM AUTHOR]