The prognostic effect of prediabetes defined by different criteria in patients with stable coronary artery disease: a prospective cohort study in Asia

To evaluate the impact of prediabetes identified by different glycemic thresholds (according to ADA or WHO/IEC criteria) and diagnostic tests (fasting plasma glucose [FPG] or hemoglobin A1c [HbA1c]) on clinical outcomes in patients with stable coronary artery disease (CAD).In this prospective cohort study, we consecutively enrolled 4088 stable CAD non-diabetic patients with a median follow-up period of 3.2 years. Prediabetes was defined according to ADA criteria as FPG 5.6∼6.9 mmol/L and/or HbA1c 5.7∼6.4%, and WHO/IEC criteria as FPG 6.1∼6.9 mmol/L and/or HbA1c 6.0∼6.4%. The primary endpoint was major adverse cardiovascular event (MACE), including all-cause death, myocardial infarction, or stroke. The prevalence of prediabetes defined according to ADA criteria (67%) was double that of WHO/IEC criteria (34%). Compared with patients with normoglycaemia, those with WHO/IEC-defined prediabetes were significantly associated with higher risk of MACE [adjusted hazard ratio (HR) 1.50, 95% confidence interval (CI) 1.10-2.06], mainly driven by the higher incidence of events in individuals with HbA1c-defined prediabetes. However, this difference was not found in patients with ADA-defined prediabetes and normoglycaemia (adjusted HR 1.17, 95% CI 0.81-1.68). Although FPG was not associated with cardiovascular events, HbA1c improved the risk prediction for MACE in a model of traditional risk factors. Furthermore, the optimal cutoff value of HbA1c for predicting MACE was 5.85%, which was close to the threshold recommended by IEC.This study supports the use of WHO/IEC criteria for the identification of prediabetes in stable CAD patients. Haemoglobin A1c, rather than FPG, should be considered as a useful marker for risk stratification in this population.Not applicable.This study, for the first time, evaluated the prognostic effect of prediabetes identified by different glycaemic thresholds (ADA or WHO/IEC criteria) and diagnostic tests (FPG or HbA1c) in individuals with stable CAD. The results of this study support the identification of individuals with prediabetes using WHO/IEC criteria in stable, angiography-proven CAD patients. Haemoglobin A1c, rather than FPG, should be considered as a useful marker for risk stratification and the optimal cutoff value of HbA1c for predicting MACE was 5.85%, which was close to the threshold of 6.0% recommended by IEC.