The aim of the study was to compare the impact of impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) on vascular function among older Chinese people. A random sample of 671 men and 603 women aged 50 to 85 years without known diabetes from the Guangzhou Biobank Study-CVD was examined in a cross-sectional study. Subjects with no previously confirmed or treated diabetes but with both lasting plasma glucose less than 5.6 mmol/L and 2-hour glucose from 7.8 to less than 11.0 mmol/L were classified as having isolated IGT, and those with no previously confirmed and treated diabetes but with both lasting plasma glucose from 5.6 to less than 7.0 mmol/L and 2-hour glucose less than 7.8 mmol/L were classified as having isolated IFG. A total of 11.0% attic men and 8.6% of the women had isolated IFG, and 17.7% of the men and 18.6% of the women had isolated IGT. The brachial-ankle pulse wave velocity and pulse pressure were increased in both the isolated IFG and isolated IGT subjects compared with the normoglycemia group (both Ps <.001). Compared with subjects with isolated IFG, those with isolated IGT appeared to have a higher age- and sex-adjusted brachial-ankle pulse wave velocity (1543 +/- 22 vs 1566 +/- 17, P = .07) and to be more insulin resistant (2-hour postload insulin: 54.2 +/- 2.13 vs 26.8 +/- 2.99 mu U/mL, P <.001), had a worse lipid profile (apolipoprotein [apo] B: 1.07 +/- 0.02 vs 0.97 +/- 0.02g/L, P <.001; apo B/apo A-1 ratio: 0.80 +/- 0.02 vs 0.69 +/- 0.02, P <.001), but had lower glycosylated hemoglobin levels (6.03% +/- 0.06% vs 5.86% +/- 0.04%, P <.001) (values arc mean +/- SE). Subjects with isolated IGT had greater arterial stillness, probably as a result of being more insulin resistant, with a worse lipid profile than those with isolated IFG. The sole use of fasting glucose level to identify prediabetic people would fail to identify a significant proportion of the at-risk population. (C) 2010 Elsevier Inc. All rights reserved.