Receiver operating characteristic analysis on fasting plasma glucose, HbA_1c, and fructosamine on diabetes screening

Objective: To determine the efficacy of HbA_1c and fructosamine as alternatives to fasting plasma glucose (FPG) for diabetes screening. Research Design and Methods: Receiver operating characteristic (ROC) analysis was conducted on the above tests. Comparison among tests was based on the area under ROC curve of a test. World Health Organization criteria for classifying glucose tolerance status of the subjects was used. The study consisted of subjects (n = 583) who visited the clinic from September to October 1989 and all diabetic cases (n = 36) from November 1989 to March 1990, after excluding those <40 yr of age or with hypoglycemic therapies (469 were normal, 88 with impaired glucose tolerance [IGT], and 62 with diabetes). Results: Area under ROC curve of HbA_1c was not different from that of FPG. Area under curve of fructosamine was significantly smaller than that of FPG. For all tests, overall efficacy of a test to detect IGT and diabetes was considerably diminished compared with detection of diabetes alone. Conclusions: The discriminating ability of HbA_1c is almost the same as that of FPG, therefore HbA_1c is a good alternative to FPG. Fructosamine is not suitable for diabetes screening.