Glucose tolerance and markers of myocardial injury after an acute coronary syndrome: predictive role of the 1-h plus 2-h plasma glucose at the oral glucose tolerance test

Objective: Impaired glucose tolerance (IGT) has been related to adverse cardiovascular outcomes. We investigated the added value of 1-h plasma glucose (PG) at the oral glucose tolerance test (OGTT) in predicting admission and peak cardiac high-sensitivity troponin T (hs-TnT) and NT-proBNP values in IGT patients admitted for an acute coronary syndrome (ACS).

Research design and methods: Among 192 consecutive ACS patients, 109 had Hb1Ac and fasting plasma glucose negative for newly diagnosed diabetes. Upon OGTT performed > 96 h after admission, 88, conventionally diagnosed as IGT, were divided into: "full glucose tolerance" (1-h PG-OGTT < 155 mg/dL and 2-h PG-OGTT < 140 mg/dL, N = 12);"early IGT" (1 h-PG-OGTT ≥ 155 mg/dL and 2-h PG-OGTT < 140 mg/dL, N = 33);"late IGT" (1-h PG-OGTT < 155 mg/dL and 2-h PG-OGTT ≥ 140 mg/dL, N = 8); and "full IGT" (1-h PG-OGTT ≥ 155 mg/dL and 2-h PG-OGTT ≥ 140 mg/dL, N = 35). The 4 groups were compared for cardiac markers.

Results: The first three groups had similar cardiac marker values, but only full IGT patients had significantly higher admission hs-TnT compared with the 3 other groups [median (interquartile range): 911 (245-2976) vs 292 (46-1131), P < 0.001]. Full IGT patients also had higher hs-TnT peak compared with fully glucose tolerant and early IGT patients. Only full IGT patients had longer hospitalization and higher NT-proBNP vs fully glucose tolerant patients (P = 0.005).

Conclusions: Among non-diabetic ACS patients, only those with both 1-h PG ≥ 155 mg/dL and 2-h PG ≥ 140 mg/dL had more severe myocardial injury and longer hospitalization. One-h PG-OGTT importantly contributes to assessing post-ACS cardiac risk.