The Prognostic Value of Fasting Plasma Glucose, Two-Hour Postload Glucose, and HbA1c in Patients With Coronary Artery Disease: A Report From EUROASPIRE IV: A Survey From the European Society of Cardiology

Abstract

Objective: Three tests are recommended for identifying dysglycemia: fasting glucose (FPG), 2-h postload glucose (2h-PG) from an oral glucose tolerance test (OGTT), and glycated hemoglobin A_1c (HbA_1c). This study explored the prognostic value of these screening tests in patients with coronary artery disease (CAD).

Research design and methods: FPG, 2h-PG, and HbA_1c were used to screen 4,004 CAD patients without a history of diabetes (age 18-80 years) for dysglycemia. The prognostic value of these tests was studied after 2 years of follow-up. The primary end point included cardiovascular mortality, nonfatal myocardial infarction, stroke, or hospitalization for heart failure and a secondary end point of incident diabetes.

Results: Complete information including all three glycemic parameters was available in 3,775 patients (94.3%), of whom 246 (6.5%) experienced the primary end point. Neither FPG nor HbA_1c predicted the primary outcome, whereas the 2h-PG, dichotomized as <7.8 vs. ≥7.8 mmol/L, was a significant predictor (hazard ratio 1.38, 95% CI 1.07-1.78; P = 0.01). During follow-up, diabetes developed in 78 of the 2,609 patients (3.0%) without diabetes at baseline. An FPG between 6.1 and 6.9 mmol/L did not predict incident diabetes, whereas HbA_1c 5.7-6.5% and 2h-PG 7.8-11.0 mmol/L were both significant independent predictors.

Conclusions: The 2h-PG, in contrast to FPG and HbA_1c, provides significant prognostic information regarding cardiovascular events in patients with CAD. Furthermore, elevated 2h-PG and HbA_1c are significant prognostic indicators of an increased risk of incident diabetes.

Figure 1

Patient flowchart including information on the components of the composite end point. CVD, cardiovascular disease; TIA, transient ischemic attack.

Figure 2

The capacity of FPG, OGTT 2h-PG, and HbA_1c to predict incident diabetes in 2,609 patients without this disease at the baseline investigation. Odds ratio (OR) 95% CI and P value adjusted for age and sex.