This study investigates the influence of changes in impaired fasting glucose (IFG) criteria by the American Diabetes Association in 2003 in estimating the prevalence and cardiovascular risks in Taiwanese with fasting plasma glucose (FPG) between 100 and 109 mg/dL. Data came from a cross-sectional study on 1411 participants aged 30 years and older without known diabetes in southern Taiwan. Besides collection of anthropometric and biochemistry data, a 75-g oral glucose tolerance test was performed. The new IFG criteria additionally identified 14.2% of all participants as having IFG100, with FPG between 100 and 109 mg/dL, among which the percentage of normal glucose tolerance (NGT), impaired glucose tolerance (IGT), and diabetes mellitus were 7.7%, 5.0%, and 1.5%, respectively. Mean body weight, body mass index, abdominal girth, systolic blood pressure, diastolic blood pressure (DBP), 2-hour glucose, and triglyceride were significantly higher in the IFG100 group than in normal fasting glucose (NFG) group (FPG, <100 mg/dL). Moreover, body weight, body mass index, systolic blood pressure, DBP, and 2-hour glucose were statistically higher in subgroups of IFG100/IGT than in NFG/NGT. In contrast, only DBP and 2-hour glucose were significantly higher in the IFG100/NGT group than in the NFG/NGT group. The 2003 criteria increased the prevalence of IFG and identified more IGT and diabetes. However, the increase of cardiovascular risks among newly identified IFG100 subjects came from those who concomitantly had IGT.