Published online Oct 15, 2016. doi: 10.4239/wjd.v7.i18.423
Peer-review started: April 8, 2016
First decision: June 12, 2016
Revised: July 22, 2016
Accepted: August 11, 2016
Article in press: August 15, 2016
Published online: October 15, 2016
Pre-diabetes, which is typically defined as blood glucose concentrations higher than normal but lower than the diabetes threshold, is a high-risk state for diabetes and cardiovascular disease development. As such, it represents three groups of individuals: Those with impaired fasting glucose (IFG), those with impaired glucose tolerance (IGT) and those with a glycated haemoglobin (HbA1c) between 39-46 mmol/mol. Several clinical trials have shown the important role of IFG, IGT and HbA1c-pre-diabetes as predictive tools for the risk of developing type 2 diabetes. Moreover, with regard to cardiovascular disease, pre-diabetes is associated with more advanced vascular damage compared with normoglycaemia, independently of confounding factors. In view of these observations, diagnosis of pre-diabetes is mandatory to prevent or delay the development of the disease and its complications; however, a number of previous studies reported that the concordance between pre-diabetes diagnoses made by IFG, IGT or HbA1c is scarce and there are conflicting data as to which of these methods best predicts cardiovascular disease. This review highlights recent studies and current controversies in the field. In consideration of the expected increased use of HbA1c as a screening tool to identify individuals with alteration of glycaemic homeostasis, we focused on the evidence regarding the ability of HbA1c as a diagnostic tool for pre-diabetes and as a useful marker in identifying patients who have an increased risk for cardiovascular disease. Finally, we reviewed the current evidence regarding non-traditional glycaemic biomarkers and their use as alternatives to or additions to traditional ones.
Core tip: Pre-diabetes is a high-risk state for diabetes and cardiovascular disease. There are three diagnostic criteria for pre-diabetes: Impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and glycated haemoglobin (HbA1c) between 39-46 mmol/mol. The concordance between a pre-diabetes diagnosis made by IFG, IGT or HbA1c is scarce and there are conflicting data as to which of these methods best predicts cardiovascular disease. This review focuses on the evidence regarding the ability of HbA1c for pre-diabetes diagnosis and as a marker for cardiovascular risk. Finally, the evidence regarding non-traditional glycaemic biomarkers as alternatives to the traditional ones is reviewed.