Admission glucose and mortality in elderly patients hospitalized with acute myocardial infarction: implications for patients with and without recognized diabetes.

BACKGROUND The relationship between admission glucose levels and outcomes in older diabetic and nondiabetic patients with acute myocardial infarction is not well defined. METHODS AND RESULTS We evaluated a national sample of elderly patients (n=141,680) hospitalized with acute myocardial infarction from 1994 to 1996. Admission glucose was analyzed as a categorical (< or =110, >110 to 140, >140 to 170, >170 to 240, >240 mg/dL) and continuous variable for its association with mortality in patients with and without recognized diabetes. A substantial proportion of hyperglycemic patients (eg, 26% of those with glucose >240 mg/dL) did not have recognized diabetes. Fewer hyperglycemic patients without known diabetes received insulin during hospitalization than diabetics with similar glucose levels (eg, glucose >240 mg/dL, 22% versus 73%; P<0.001). Higher glucose levels were associated with greater risk of 30-day mortality in patients without known diabetes (for glucose range from < or =110 to >240 mg/dL, 10% to 39%) compared with diabetics (range, 16% to 24%; P for interaction <0.001). After multivariable adjustment, higher glucose levels continued to be associated with a graded increase in 30-day mortality in patients without known diabetes (referent, glucose < or =110 mg/dL; range from glucose >110 to 140 mg/dL: hazard ratio [HR], 1.17; 95% CI, 1.11 to 1.24; to glucose >240 mg/dL: HR, 1.87; 95% CI, 1.75 to 2.00). In contrast, among diabetic patients, greater mortality risk was observed only in those with glucose >240 mg/dL (HR, 1.32; 95% CI, 1.17 to 1.50 versus glucose < or =110 mg/dL; P for interaction <0.001). One-year mortality results were similar. CONCLUSIONS Elevated glucose is common, rarely treated, and associated with increased mortality risk in elderly acute myocardial infarction patients, particularly those without recognized diabetes.