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 ≥7.8 mmol/L and <11.1 mmol/L (group 2), and 36 patients with admission glucose ≥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 Hb_A1c (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 Hb_A1c 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 Hb_A1c, 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.