Detection of glucose intolerance after heart attack

A Swedish study in this week's issue of THE LANCET confirms that people admitted to hospital with an acute heart attack are at an increased risk of having undiagnosed diabetes or increased glucose intolerance. Findings of the new study suggest that the fasting glucose of patients or high glucose concentrations immediately after heart attack could be a marker of patients at high risk of subsequent cardiovascular disease.

People with diabetes who have myocardial infarction (heart attack) are more likely to die than those without diabetes. Previous research indicates that people with prediabetic conditions, such as impaired glucose tolerance, have an increased risk of cardiovascular disease, and that a blood glucose concentration below the threshold for diabetes is associated with coronary artery disease. Anna Norhammar from the Karolinska Hospital, Stockholm, Sweden, and colleagues aimed to find out the prevalence of impaired glucose metabolism in patients with myocardial infarction but in whom diabetes had not been diagnosed.

181 patients admitted to two Swedish coronary care units with acute myocardial infarction and no diagnosis of diabetes were studied. The investigators recorded glucose concentrations during the hospital stay, and did standardised oral glucose tolerance tests with 75 g of glucose at discharge (four to five days after admission) and again 3 months later.

35% and 40% of patients had impaired glucose tolerance at hospital discharge and after three months, respectively. 31% and 25%, respectively, had previously undiagnosed diabetes. Concentrations of glucose in red blood cells at hospital admission and fasting blood glucose concentrations at discharge were independent predictors of abnormal glucose tolerance.

In an accompanying Commentary, Stephen Haffner from the University of Texas, USA, states: "…in view of the high risk of future coronary heart disease in patients with diabetes, it is reasonable to suggest an oral glucose-tolerance test at discharge after a myocardial infarction. Although the glucose-tolerance test is burdensome for screening in the general population, it is less so in hospitalised patients. The high frequency of newly discovered diabetes is also important because intensive glycaemic control with insulin during the peri-infarction period followed by improved glycaemic control as outpatients lowers the mortality from acute myocardial infarction."

Contact: Professor Lars Rydén, Department of Cardiology, Karolinska Hospital, 171 76 Stockholm, Sweden; T) +46 8 5177 2171; F) +46 8 311044; E) lars.ryden@ks.se

Professor Stephen M Haffner, University of Texas Health Science Center at San Antonio, Department of Medicine, San Antonio, TX 78229-3900, USA; E) haffner@uthscsa.edu

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