Is admission hyperglycaemia in non-diabetic patients with acute myocardial infarction a surrogate for previously undiagnosed abnormal glucose tolerance?

AIMS: To investigate whether admission hyperglycaemia in non-diabetic patients with acute myocardial infarction (AMI) is a surrogate for previously undiagnosed abnormal glucose tolerance. METHODS AND
RESULTS: Two hundred non-diabetic patients with AMI were divided into three groups: 81 patients with admission glucose < 7.8 mmol/L (group 1), 83 patients with admission glucose > or = 7.8 mmol/L and < 11.1 mmol/L (group 2), and 36 patients with admission glucose > or = 11.1 mmol/L (group 3). Abnormal glucose tolerance, diabetes, or impaired glucose tolerance (IGT) was diagnosed by oral glucose tolerance test (OGTT). OGTT identified diabetes in 53 patients (27%) and IGT in 78 patients (39%). When the fasting glucose criteria were applied, however, only 14 patients (7%) were diagnosed as having diabetes. The prevalence of abnormal glucose tolerance was similar among the three groups: 67% in group 1, 63% in group 2, and 69% in group 3 (P = 0.74). The relation of fasting glucose (r2 = 0.50, P < 0.001) and HbA1c (r2 = 0.34, P < 0.001) to 2-h post-load glucose was significant, but the relation of admission glucose to 2-h post-load glucose was not significant (r2 = 0.02, P = 0.08). Multivariable analysis showed that fasting glucose and HbA1c were independent predictors of abnormal glucose tolerance, but admission glucose was not.
CONCLUSION: Admission hyperglycaemia in non-diabetic patients with AMI does not represent previously undiagnosed abnormal glucose tolerance. Fasting glucose and HbA1c, rather than admission glucose, may be useful to predict abnormal glucose tolerance. However, these parameters lacked sensitivity. OGTT should be considered in all non-diabetic patients with AMI.