Performance of an A1C and fasting capillary blood glucose test for screening newly diagnosed diabetes and pre-diabetes defined by an oral glucose tolerance test in Qingdao, China

Abstract

OBJECTIVE - The study's goal was to evaluate the performance of A1C and fasting capillary blood glucose (FCG) tests as mass screening tools for diabetes and pre-diabetes, as determined by the standard oral glucose tolerance test (OGTT). RESEARCH DESIGN AND METHODS - Data from 2,332 individuals aged 35-74 years who participated in a population-based cross-sectional diabetes survey in Qingdao, China, were analyzed. A 2-h 75-g OGTT was used to diagnose diabetes. The performance of A1C and FCG was evaluated against the results of the OGTTs by using receiver operating characteristic curve (ROC) analysis. RESULTS - The prevalence of newly diagnosed diabetes and pre-diabetes (impaired fasting glucose and/or impaired glucose tolerance) was 11.9 and 29.5%, respectively. For subjects with newly diagnosed diabetes, the area under the ROC curve was 0.67 for A1C and 0.77 for FCG (P < 0.01) in men and 0.67 and 0.75 (P < 0.01) in women, whereas for pre-diabetes, these values were 0.47 and 0.64 (P < 0.001) in men and 0.51 and 0.65 (P < 0.001) in women. At the optimal A1C cutoff point of ≥5.6% for newly diagnosed diabetes, sensitivities (specificities) were 64.4% (61.6%) for men and 62.3% (63.3%) for women. CONCLUSIONS - As a screening tool for newly diagnosed diabetes and pre-diabetes, the FCG measurement performed better than A1C in this general Chinese population. © 2010 by the American Diabetes Association.