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 (<= 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 > 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 <= 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 <= 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.