LAUSR

AIMS To evaluate the prognostic 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]) in patients with stable coronary artery disease (CAD). METHODS In this prospective cohort study, we consecutively enrolled 4,088 stable CAD nondiabetic 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∼6.9mmol/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. RESULTS The prevalence of prediabetes defined according to ADA criteria (67%) was double that of WHO/IEC criteria (34%). Compared with patients with normoglycemia, those with WHO/IEC-defined prediabetes were significantly associated with higher risk of MACE (adjusted HR 1.50, 95%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 normoglycemia (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. CONCLUSION This study supports the use of WHO/IEC criteria for the identification of prediabetes in stable CAD patients. HbA1c, rather than FPG, should be considered as a useful marker for risk stratification in this population. TRIAL REGISTRATION not applicable.