Aims:
Three methods are used to identify dysglycaemia: fasting plasma glucose (FPG), 2-h post-load plasma glucose (2hPG) from the oral glucose tolerance test (OGTT), and glycated haemoglobin A1c (HbA1c). The aim was to describe the yield and concordance of FPG, HbA1c, and 2hPG alone, or in combination, to identify dysglycaemia in patients with coronary artery disease.

Methods and results:
In EUROASPIRE IV, a cross-sectional survey of patients aged 18–80 years with coronary artery disease in 24 European countries, 4004 patients with no reported history of diabetes had FPG, 2hPG, and HbA1c measured. All participants were divided into different glycaemic categories according to the ADA and WHO criteria for dysglycaemia. Using all screening tests together, 1158 (29%) had undetected diabetes. Out of them, the proportion identified by FPG was 75%, by 2hPG 40%, by HbA1c 17%, by FPG + HbA1c 81%, and by OGTT (=FPG + 2hPG) 96%. Only 7% were detected by all three methods FPG, 2hPG, and HbA1c. The ADA criteria (FPG + HbA1c) identified 90% of the population as having dysglycaemia compared with 73% with the WHO criteria (OGTT = FPG + 2hPG). Screening according to the ADA criteria for FPG + HbA1c identified 2643 (66%) as having a ‘high risk for diabetes’, while the WHO criteria for FPG + 2hPG identified 1829 patients (46%).

Conclusion:
In patients with established coronary artery disease, the OGTT identifies the largest number of patients with previously undiagnosed diabetes and should be the preferred test when assessing the glycaemic state of such patients.