Objective: To assess the association between impaired fasting glucose and overall and cardiovascular disease (CVD) mortality among Korean adults. Methods: From the nationwide cohort provided by the National Health Insurance Service in Korea (2002-2013), subjects were stratified as normal glucose tolerance (NGT, fasting glucose < 100 mg/dL), impaired fasting glucose (IFG) stage 1 (100~109 mg/dL), IFG stage 2 (110~125 mg/dL), and diabetes mellitus (DM) groups based on serum fasting glucose level. Overall and CVD mortality risks were assessed by Cox regression analyses. Results: When adjusted for age, sex, and body mass index, IFG stage 2 was associated with significantly higher all-cause mortality (HR, 1.26, 95% CI: 1.18-1.34), and CVD mortality (HR, 1.27, 95% CI: 1.08-1.49) compared to NGT. However, IFG stage 1 was not associated with increased risk of mortality from any causes. Among CVD category, mortality from ischemic stroke was significantly higher (HR, 1.60, 95% CI: 1.18-2.18) in subjects with IFG stage 2, but not mortality from ischemic heart disease. The ischemic stroke mortality in IFG stage 2 remained elevated when other CVD risk factors including smoking, physical activity, systolic blood pressure, and total cholesterol were adjusted for. Conclusion: Higher degree of IFG (110~125 mg/dL of fasting glucose) was associated with increased all-cause and CVD mortality. The increased risk of CVD mortality in IFG was attributable to ischemic stroke, not ischemic heart disease among Korean adults.