Impaired fasting glucose and cardiovascular outcomes in postmenopausal women with coronary artery disease

Background: Type 2 diabetes increases risk for cardiovascular disease. Persons with impaired fasting glucose levels may also have increased risk. Objective: To evaluate the association between glucose status and cardiovascular outcomes and the effect of lowering the fasting glucose level criterion for impaired fasting glucose from a lower limit of 6.1 mmol/L (110 mg/dL) to 5.6 mmol/L (100 mg/dL). Design: Prospective cohort study. Setting: 20 U.S. clinical centers. Patients: 2763 postmenopausal women with established coronary heart disease (CHD) who were followed for 6.8 years. Measurements: Any CHD event (nonfatal myocardial infarction or CHD death), stroke or transient ischemic attack (TIA), congestive heart failure (CHF) hospitalization, and any cardiovascular event. Results: During follow-up, 583 women had a CHD event, 329 women had a stroke or TIA, and 348 women were hospitalized for CHF. Women with diabetes were at an approximately 75% increased risk for each outcome compared with normoglycemic women. The 218 women with impaired fasting glucose according to the 1997 definition (fasting glucose level, 6.1 to 6.9 mmol/L [110 to 125 mg/dL]) had increased risk for any CHID event (hazard ratio, 1.37 [95% CI, 1.08 to 1.74]), while the 698 women with impaired fasting glucose according to the 2003 definition (fasting glucose level, 5.6 to 6.9 mmol/L [100 to 125 mg/dL]) were not at increased risk (hazard ratio, 1.09 [CI, 0.90 to 1.34]). Most of the women (n = 480) with fasting glucose levels between 5.6 mmol/L (100 mg/dL) and 6.0 mmol/L (109 mg/dL) had no increased risk for CHD (hazard ratio, 0.90 [CI, 0.73 to 1.12]). Women with impaired fasting glucose according to either definition were not at increased risk for stroke or TIA or CHF. Limitations: These findings may not be generalizable to men or women without existing heart disease. Conclusions: Among postmenopausal women with coronary artery disease, the 2003 definition for impaired fasting glucose was not associated with increased risk for new CHID, stroke or TIA, or CHF.