Modifying cardiovascular risk in diabetes mellitus.

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DIABETES mellitus affects an estimated 35 million people in the United States, and the disease prevalence is predicted to increase by nearly 200% in the next several decades. As a result, anesthesiologists will be confronted with an increasing population of patients undergoing anesthesia and surgery who are at risk for ischemic heart disease. Hyperglycemia Predicts Cardiovascular Risk Diabetes is a significant predictor of perioperative cardiovascular morbidity and mortality, but few studies have evaluated methods to modify this risk. Compelling evidence indicates that aggressive management of diabetes may substantially decrease the adverse consequences of myocardial ischemia and infarction. The direct impact of hyperglycemia on cardiovascular mortality in patients with and without diabetes is a central theme of current research, and several investigations conducted during the past 20 yr demonstrated that mortality resulting from acute myocardial infarction (AMI) is increased if blood glucose concentration is elevated at the time of hospital admission. 1 These findings were confirmed in a recent prospective analysis of 336 consecutive patients admitted with AMI. 2 One-year mortality was 9% for patients with AMI and normal admission blood glucose values. In contrast, patients with hyperglycemia (blood glucose concentrations of 121 15, 168 13, and 282 65 mg/dl) on admission demonstrated substantial increases (P 0.005) in mortality to 13, 30, and 44%, respectively. 2 The Diabetes and Insulin-Glucose Infusion in Acute Myocardial Infarction (DIGAMI) trial addressed the prognostic significance of hyperglycemia in patients with type 1 and 2 diabetes and AMI. 3 A nearly linear relationship between blood glucose concentration on admission and long-term mortality was observed in conventionally treated patients in this randomized clinical trial (mortality rates of 35, 40, and 55% at blood glucose concentrations of 235, 235–298, and 298 mg/dl, respectively). A direct relationship between fasting blood glucose concentration and the risk of sustaining a cardiovascular event (e.g., sudden cardiac death, AMI, or cerebrovascular accident) has been demonstrated in a meta-regression analysis of data from 20 studies involving more than 95,000 patients. 4 The risk associated with fasting blood glucose concentrations was linear and extended below the threshold used to define diabetes. A fasting blood glucose value of only 110 mg/dl was associated with an increased relative risk of a cardiovascular event. Similarly, the odds ratio of AMI was increased to 1.5, 3.4, and 6.0 at fasting blood glucose concentrations of approximately 90, 110, and greater than 115 mg/dl, respectively. 5 Another large cohort study indicated that glycosylated hemoglobin (HbA1c) concentration, but not the presence of diabetes, predicted an increase in mortality. 6 The risk of all-cause mortality increased by a factor of 1.46 for every 1% increase in HbA 1c when male patients with diabetes, those with HbA 1c concentrations greater than 7%, or patients with a history of heart disease or stroke were excluded from the multivariate regression model. Similarly, creatinine kinase concentrations were higher in patients with hyperglycemia admitted with AMI compared with those with normal blood glucose levels. 2 These data demonstrate a striking relationship