16 Impaired glucose tolerance and cardiovascular outcomes after an acute coronary syndrome—the important role of 1-h plasma glucose at the oral glucose tolerance test

Abstract

Abstract Aims 2-h plasma glucose (PG) ≥140 mg/dl but <200 mg/dl at the oral glucose tolerance test (OGT), defined as impaired glucose tolerance (IGT), has been reported as related to adverse cardiovascular outcomes in non-diabetic patients. The added value of 1-h plasma glucose (PG) ≥155 mg/dl at the OGTT is unknown. We investigated the value of 1-h PG in IGT patients admitted for an acute coronary syndrome (ACS) in relation to in hospital outcome. Methods and results Among 109 patients admitted to Coronary Care Unit for an ACS, with both no previous diagnosis of diabetes and first-line in-hospital screening with glycated haemoglobin (HbA1c) and fasting plasma glucose (FPG) negative for either diabetes and prediabetes, OGTT was performed. On the basis of the OGTT results, 21 patients (19.3%) were newly diagnosed diabetes. The remaining 88 patients were divided into: Group A: ‘fully glucose tolerant’, with 1 h PG-OGTT <155 mg/dl and 2 h PG-OGTT <140 mg/dl; Group B: ‘early-impaired IGT’ with 1 h-PG at OGTT ≥155 mg/dl and 2 h-PG <140 mg/dl; Group C: ‘late impaired-IGT’, with 1 h-PG at OGTT <155 mg/dl and 2 h PG-OGTT ≥140 mg/dl; and Group D: ‘fully impaired IGT’, with 1 h-PG at OGTT ≥155 mg/dl and 2 h PG-OGTT ≥140 mg/dl. In this analysis we compared the four groups as to cardiac markers and days of hospitalization by the Kruskal–Wallis test and correcting multiple comparisons with the Bonferroni’s adjustment. On the basis of the OGTT results, 12 patients (13.5%) belonged to Group A, 32 (39%) to Group B, 8 (9%) to Group C, and 35 (39%) patients to Group D. Group D patients had significant higher Hs-TnT at admission compared to Group A (P = 0.013), Group B (P = 0.023), and Group C (P = 0.005). Group D patients featured significant higher Hs-TnT peak compared to Group A (P = 0.016) and Group B (P = 0.005). Patients in Group D had a longer hospitalization compared to Group A (P = 0.005). Conclusions In the setting of ACS, compared to non-diabetic patients with a normal OGTT, only IGT patients characterized by both 1 h-PG ≥155 mg/dl and 2 h PG ≥ 140 mg/dl had more severe myocardial injury and longer hospitalization. These results suggest that, within currently defined IGT patients, 1 h-PG importantly contributes to assessing cardiac risk.