Review Newly detected abnormal glucose regulation and long-term prognosis after acute myocardial infarction: Comparison of an oral glucose tolerance test and glycosylated haemoglobin A1c Gokulan Pararajasingam a, ⁎ ,1 , Dan Eik Høfsten b,1 , Brian Bridal Løgstrup c,1 , Michael Egstrup b,1 , Finn Lund Henriksen d,1 , Jørgen Hangaard e,1 , Kenneth Egstrup a,1 a Department of Medical Research, OUH Svendborg Hospital, Valdemarsgade 53, 5700 Svendborg, Denmark b Department of Cardiology, Copenhagen University Hospital Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark c Department of Cardiology, Aarhus University Hospital Skejby, Palle Juul-Jensens Boulevard 99, 8200 Aarhus, Denmark d Department of Cardiology, Odense University Hospital, Sdr. Boulevard 29, 5000 Odense, Denmark e Department of Endocrinology, OUH Svendborg Hospital, Valdemarsgade 53, 5700 Svendborg, Denmark abstract article info Article history: Received 9 July 2014 Received in revised form 29 February 2016 Accepted 29 March 2016 Available online 31 March 2016 Background: An oral glucose tolerance test (OGTT) and/or glycosylated haemoglobin A1c (HbA1c) in patients with acute myocardial infarction (AMI) identify patients with increased mortality risk, but no comparison of the long-term prognostic values has yet been investigated. Methods: This study was a prospective cohort enrolling patients with AMI between 2002 until 2008 and follow- up until 1st October, 2012. Patients without known diabetes mellitus (DM) underwent an OGTT. Seventy-nine patients with known DM did not have an OGTT performed. Primary endpoint was all-cause mortality. We includ- ed 548 patients with AMI, of whom 469 underwent a standardized OGTT and were stratified according to OGTT and HbA1c. Results: During 9.8 years of follow-up, 179 (33%) patients died. In patients having increased HbA1c ≥ 6.5%, a significantly increased mortality was observed (Hazard Ratio (HR) 1.60 [1.09–2.34]). However, when adjusting for known DM, no significance was detected. An OGTT did not show a significantly increased mortality, if used separately. A combined estimate showed a significantly increased mortality in patients categorized as newly di- agnosed DM by OGTT and HbA1c b 6.5% (HR 1.56 [95% CI 1.07–2.30]) compared to patients categorized as nor- mal/impaired fasting glycaemia/impaired glucose tolerance by OGTT and HbA1c b 6.5%. Approximately 50% of the patients with newly diagnosed DM by OGTT were only detected due to 2-hour post-load glucose values. Conclusion: An OGTT is recommended in AMI patients without known DM and HbA1c b 6.5%. Patients categorized as newly diagnosed DM by OGTT although HbA1c b 6.5% share the same high risk of mortality as patients with HbA1c ≥ 6.5%. © 2016 Elsevier Ireland Ltd. All rights reserved. Keywords: oral glucose tolerance test acute myocardial infarction glycosylated haemoglobin mortality follow-up 1. Introduction Diabetes mellitus (DM) is a well-established risk factor for cardiovas- cular morbidity and mortality [1,2]. Glucose levels below the diabetic threshold are also risk factors for cardiovascular morbidity and mortality [3]. Several studies using an oral glucose tolerance test (OGTT) have dem- onstrated a high prevalence of abnormal glucose values (dysglycaemia) in patients admitted with acute myocardial infarction (AMI), and identi- fied these patients as a high-risk population with increased mortality [4–6]. Furthermore, patients with dysglycaemia were observed with higher mortality rates compared to those with no dysglycaemia [1,4]. The World Health Organization (WHO) criteria for diagnosing DM by an OGTT were based on venous plasma glucose ≥ 11.1 mmol/l after a 75 g oral glucose challenge. In addition, WHO and American Diabetes As- sociation (ADA) added the use of HbA1c ≥ 6.5% as a diagnostic criterion for DM [7–9]. HbA1c has been used to monitor the effectiveness of glycaemic control in diabetic patients [10]. However, since its introduc- tion as a diagnostic tool, it has been debated whether the chosen thresh- old is adequate to identify high-risk patients [11–13], as it was mainly chosen to identify patients with a high risk of developing microvascular diabetic complications (i.e. retinopathy and micro albuminuria) [14,15]. The aim of this study was to assess the prognostic value of HbA1c compared to an OGTT on all-cause mortality in patients admitted with International Journal of Cardiology 214 (2016) 310–315 ⁎ Corresponding author. E-mail address: gokulan.pararajasingam@rsyd.dk (G. Pararajasingam). 1 This author takes responsibility for all aspects of the reliability and freedom from bias of the data presented and their discussed interpretation. http://dx.doi.org/10.1016/j.ijcard.2016.03.199 0167-5273/© 2016 Elsevier Ireland Ltd. All rights reserved. Contents lists available at ScienceDirect International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard