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

Abstract

Background/Aims: 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. Methodology: 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. Results: 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 ((B)=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. Conclusions: In NAFLD patients, an HbA1c concentration of 5.8% or higher can be used as an index for predicting abnormal postprandial glucose tolerance.