Fasting but not postprandial (postmeal) glycemia predicts the risk of death in subjects with coronary artery disease

BACKGROUND: Chronic hyperglycemia plays a role in the pathogenesis of coronary artery disease (CAD); however, the cut-off level beyond which glycemia becomes detrimental is still controversial. Postprandial glycemia may be a stronger CAD risk factor than fasting glycemia in patients without documented heart disease. OBJECTIVES: To identify the contributions of fasting and postprandial glycemia to cardiovascular risk in patients with documented coronary artery disease. METHODS: The Coronary Artery Surgery Study (CASS) registry is a database of 24,958 patients with suspected or proven CAD who underwent cardiac catheterization between 1974 and 1979. Median long-term follow up was 14.7 years (interquartile range 9.8 to 16.5 years). Clinical outcomes were evaluated according to fasting glucose levels and 2 h postprandial (postmeal) plasma glucose (2hPG) levels. A total of 13,176 patients with baseline fasting glucose levels and 1691 patients with 2hPG levels were identified. RESULTS: Impaired fasting glycemia was associated with a 1.2-fold increase in both all-cause and cardiovascular mortality (adjusted hazard ratio 1.23; 95% CI 1.08 to 1.40 for cardiovascular mortality), while undiagnosed diabetes was associated with a 1.5-fold increased risk for the same end points. Postprandial by hyperglycemia (2hPG of 7.8 mmol/L I p to 11.0 mmol/L following an average meal) was not associated with a significant risk of death after adjustment for traditional risk factors or in the presence of fasting glucose of less than 6.1 mmol/L. CONCLUSIONS: In CAD patients, impaired fasting glucose is associated with increased all-cause and cardiovascular mortality, whereas postprandial hyperglycemia following an average meal does not appear to be a risk factor.