The Clinical Significance of HbA1c as a Predictive Factor for Abnormal Postprandial Glucose Metabolism in NAFLD Patients with an Elevated Liver Chemistry

Abstract

NAFLD patients often show normal fasting glucose levels despite having abnormal postprandial glucose levels. This study is aimed at examining the possibility of utilizing HbA1c as a surrogate marker for abnormal glucose tolerance in NAFLD. This study was conducted on ninety-one NAFLD patients exhibiting elevated liver enzyme. Oral glucose tolerance tests (OGTT) (75g) were performed. Insulin concentrations were measured in a fasting state, and again at 120 minutes. Sixteen subjects (44.7%) showed abnormal postprandial glucose levels among subjects with normal fasting glucose level (<100mg/dL). Among subjects whose fasting glucose levels were within the 100-125mg/dL range, 30 patients (68.2%) showed abnormal OGTT findings and 13 patients (29.5%) were diagnosed as diabetics. In univariate analysis, the predictive factors for abnormal glucose tolerance were found to be HbA1c, age, fasting glucose and 120-minute insulin. However, in multivariate analysis, only HbA1c was found to be a significant predictive factor ((β)=0.43, p=0.017). The mean values for HbA1c were higher in the diabetes (6.2%) and glucose intolerance groups (5.8%) than in the normal group (5.5%). Using HbA1c 5.8% as the cut-off level in AUROC, sensitivity and specificity for predicting abnormal OGTT were 71.0% and 89.9%. Of NAFLD patients who showed HbA1c concentrations of 5.8% or higher, 90.9% showed abnormal OGTT. In NAFLD patients, an HbA1c concentration of 5.8% or higher can be used as an index for predicting abnormal postprandial glucose tolerance.