OBJECTIVE: To assess whether the relationship between abnormal fasting plasma glucose (FPG) levels and patient outcomes holds for both older men and older women with acute myocardial infarction (AMI). PATIENTS AND METHODS: From April 1, 2004, to October 31, 2006, a total of 2016 consecutive older patients (age >= 65 years) presenting with AMI were screened. Of these patients, 1854 were consecutively enrolled in the study. Patients were categorized into 4 groups: the hypoglycemic group (FPG, <= 90.0 mg/dL [to convert to mmol/L, multiply by 0.0555]; n=443, 23.9%), the euglycemic group (FPG, 90.1-126.0 mg/dL; n=812, 43.8%), the mildly hyperglycemic group (FPG, 126.1-162.0 mg/dL; n=308, 16.6%), and the severely hyperglycemic group (FPG, >= 162.1 mg/dL; n=291, 15.7%). The primary outcomes were rates of in-hospital and 3-year mortality. RESULTS: Female patients were older and had a higher incidence of diabetes mellitus but lower rates of smoking and use of invasive therapy. Men tended to have a higher frequency of hypoglycemia, whereas women tended to have a higher frequency of hyperglycemia. No significant difference was found in in-hospital (10.9% vs 9.1%; P=.36) or 3-year (24.5% vs 24.5%; P=.99) mortality between male and female patients, and FPG-associated mortality did not vary significantly by sex. CONCLUSION: An increased FPG level was associated with a relatively higher risk of in-hospital mortality in men but not in women. Nonetheless, increased and decreased FPG levels at admission could predict higher mortality rates regardless of sex. There was a striking U-shaped relationship between FPG levels and in-hospital and 3-year mortality. The effect of abnormal FPG level on outcomes among older patients with AMI did not vary significantly by sex.