Value of blood glycosylated hemoglobin detection in screening patients with impaired glucose tolerance

Abstract

Objective To explore the value of blood glycosylated hemoglobin detection in identifying patients with impaired glucose tolerance (IGT) from those undergoing health examination.Methods 489 residents in Guangzhou region undergoing health examination suffered an oral glucose tolerance test (OGTT)as well as blood glycosylated hemoglobin (HbA1c) detection.Based on the results of OGTT as diagnostic standards,receiver operating characteristic (ROC) analysis were performed to obtain the Area under the ROC curve (AUC),the optimal thresholds,the thresholds of having about 95％ sensibility and the thresholds of having about 95％ specificity when using HbA1c and fasting plasma glucose (FPG) alone as a diagnostic test,respectively.Some indexes,such as youden index (YI),sensitivity (Sn),specificity (Sp),positive predictive value (+PV),negative predictive value (-PV),positive likelihood ratio (+LR) and negative likelihood ratio (-LR),were computed when IGT was diagnosed with HbA1c alone,FPG alone and combination tests that one of the three thresholds metioned above from HbA1c was matched with that from FPG each other,respectively.Results The AUC for HbA1c and FPG to diagnose IGT was 0.605 and 0.679,respectively.At the optimal threshold of 6.05％ for HbAlc and 5.465 mmol/L for FPG,YI was 0.186 and 0.265,Sn was 40.3％ and 56.9％,Sp was 78.3％ and 69.6％,+PV was 43.6％ and 43.9％,-PV was 75.8％ and 79.5％,+LR was 1.853 and 1.871,-LR was 0.763 and 0.619,for HbA1c and FPG,respectively.Of the combination tests the best one had a YI of 0.282,a Sn of 61.8％,a Sp of 66.4％,a +PV of 43.4％,a-PV of 80.6,a +LR of 1.838 and a-LR of 0.575.Conclusion Neither HbA1c alone nor HbAIc combined with FPG is available in screening patients with impaired glucose tolerance among subjects undergoing health examination. Key words: Glycosylated hemoglobin; Impaired glucose tolerance (IGT); Screening