We sought to clarify whether impaired fasting glucose (IFG), impaired glucose tolerance (IGT) or both (IFG/IGT) represent the most severe impairment in insulin resistance (IR) and insulin secretion. Among the 159 Chinese subjects, 21 were diagnosed as having IFG, 103 as having IGT and 35 as having both. IR and beta-cell function were assessed using homeostatic model assessment (HOMA) and an insulin-suppression test (IST). No differences were evident between the groups in blood pressure, body mass index, plasma insulin fasting levels and lipid profiles. However, plasma 2-h insulin levels were higher in the IGT and IFG/IGT groups. Beta-cell functions were not different between these groups. But, the result of glucose tolerance was different, in which the IFG/IGT and IFG groups displayed higher insulin sensitivity than IGT via HOMA instead of no difference via IST in the three patient groups.