Isolated post-challenge hyperglycaemia predicts increased cardiovascular mortality

Abstract

ObjectiveThe American Diabetes Association (ADA) has revised the criteria for the diagnosis of diabetes in 2010. Glycated haemoglobin at a cut-point of ≥6.5% has been included in the diagnostic algorithm. We aimed to investigate whether there is still the need to perform oral glucose tolerance tests (OGTT). MethodsWe studied 2002 people referred for angiography who did not have a history of diabetes. OGTT were performed in all 1772 subjects with fasting glucose <126 mg/dl. Participants were prospectively followed for all-cause and cardiovascular mortality over a mean duration (±standard deviation) of 7.7 ± 2.0 years. ResultsUsing the ADA 2010 criteria 618 individuals were categorised as having new-onset type 2 diabetes. Among these, 167 had isolated post-challenge hyperglycaemia. A total of 346 participants died during follow-up. Cardiovascular death occurred in 202 cases. Those with elevated fasting glucose ≥126 mg/dl and/or glycated haemoglobin ≥6.5% had increased all-cause (hazard ratio [HR]: 1.63, 95% confidence interval [95%CI]: 1.28–2.08, p < 0.001) and cardiovascular mortality (HR: 1.66, 95%CI: 1.21–2.29, p = 0.002) compared to subjects without diabetes according to the ADA 2010 definition. Isolated elevation of post-challenge glucose independently predicted increased cardiovascular mortality (HR: 1.57, 95%CI: 1.02–2.43, p = 0.041). All-cause and cardiovascular mortality were not significantly different between subjects with increased fasting glucose and/or glycated haemoglobin and those with isolated elevation of post-challenge glucose. ConclusionsPerforming OGTT will identify a high risk group for cardiovascular mortality undetected by fasting glucose or glycated haemoglobin.