Abstract P056: Prognostic Cut-Points of Prediabetic Plasma Glucose and HbA1c Values in Predicting Cardiovascular Disease Morbidity and Mortality: A Systematic Review and Meta-Analysis

Abstract

Background: Prediabetes are often characterized by various measurements of elevated but non-diabetic glucose values, including impaired fasting glucose (IFG), 2-hour impaired glucose tolerance (IGT), and glycosylated hemoglobin A1c (HbA1c), and represent increased risk for cardiovascular disease (CVD) morbidity and mortality. However, it remains unclear how each glucose measurement differs in their abilities to predict risk for CVD outcomes. Currently, the World Health Organization (WHO) and the American Diabetes Association (ADA) also differ in their IFG definitions, and there has been debate as to which definition best predicts future CVD risk. Objectives: In this systematic review and meta-analysis, we sought to evaluate the prognostic value of different cut-points of non-diabetic glucose measurements (IFG, IGT, and HbA1c) for predicting CVD morbidity and mortality in individuals at increased risk. Methods: We searched the MEDLINE, PubMed, Embase, Clinicaltrials.gov, World Health Organization (WHO) International Clinical Trials Registry Platform, and Cochrane database. We searched prospective cohort studies in adults without diabetes aged 18 years or older, or control groups in clinical trials, with a minimum follow-up of 3 years. We included studies that reported an association between any of the glucose measurements with CVD morbidity, including non-fatal myocardial infarction, non-fatal stroke, peripheral artery disease, a composite measure of any CVD outcomes, and CVD mortality. Retrospective cohort studies will only be investigated if there are not at least two prospective cohort studies for a given outcome. Data from eligible studies were pooled to synthesize results for each glucose measurement. Random effect model was used to calculate pooled hazard ratio or relative risk data. Results: We screened over 4,000 abstracts and identified 170 eligible prospective cohort studies with 2,826,296 individuals, with a mean follow-up of 10.2 years. Compared to individuals with normal glycaemia, individuals with IFG defined by the WHO criteria had 1.11 and 1.21 times increased risk for CVD morbidity and mortality, respectively. There was no significant increase in risk among those with IFG diagnosed by the ADA criteria compared to those with normal glycaemia. Compared to those with normal glycaemia, individuals with IGT had 1.15 and 1.24 times higher risk for CVD morbidity and mortality, respectively. HbA1c as low as 5.5% was associated with an increased risk of CVD outcomes. Conclusions: The WHO criteria for IFG seems to be a better predictor of CVD outcomes than the ADA criteria. The current criteria for IGT is a slightly strong predictor for CVD events and mortality than IFG. HbA1c levels as low as 5.5% could be used as a predictor for adverse health outcomes in non-diabetic individuals.