Object: Although the fasting plasma glucose (FPG) is a useful indicator for screening and diagnosing diabetes mellitus, there is a lack of data on the association between FPG and mortality rate in the general population. Methods: A total of 326,547 Korean adults over 20 years of age, who had received a health checkup between January 1, 2006 and December 31, 2008, were selected from the Korean National Health Insurance Service sample cohort dataset, and followed up until December 31, 2015. We measured the odds ratios (OR) of all-cause mortality and major causes of death such as malignant neoplasm, cardiovascular disease (CVD), infectious disease, and renal disease relative to FPG levels at various ranges. Results: During follow-up of 8.4 years, total deaths of 13,536 (4.89/1,000 person-year) occurred; 4,916 deaths from cancer, 2,133 from CVD, 762 from infectious disease, 199 from renal disease, and 5,526 from other causes. Compared with the reference group (FPG 80-89 mg/dL), the overall mortality rate increased with an increase in FPG category (OR 2.62, 95% CI 2.38-2.89, in category of >=200 mg/dL group, P < 0.001). In multivariable-adjusted OR analyses, J-shaped associations were found between FPG levels and mortality from overall cause after adjustment for age, sex, body mass index, smoking status, alcohol consumption, and physical exercise. This J-shape pattern was more prominent in older (over 65-year-old), obese population, and subjects without a previous history of CVD. Conclusion: In conclusions, in addition to FPG level of above normal range, FPG level of < 70 mg/dL was also associated with an increased risk of all-cause and cause-specific mortality.