Prevalence of autoantibodies against IA-2 (IA-2A), glutamic acid decarboxylase (GADA), and type II DNA topoisomerase (TopIIA) of Taiwanese type I diabetes mellitus (TIDM) patients was investigated. Correlations of these autoantibodies with patients' clinical manifestations were also analyzed. Prevalence of IA-2A, GADA, and TopIIA in our patients was 23.6%, 47.1%, and 55.2%, respectively. Eighty percent of the IA-2A recognized the carboxyl terminus of the IA-2 protein tyrosine phosphatase-like domain. Average disease duration of IA-2A(+) patients was significantly shorter than that of IA-2A(-) patients [3.76 +/- 0.42 vs. 4.98 +/- 0.34 years,p = 0.028]. Presence of GADA was correlated with the mean age of onset [10.82 +/- 0.76 vs. 8.38 +/- 0.77 years for GADA(+) and GADA(-) patients, p = 0.026]. Patients with adolescent onset have higher GADA prevalence and better residual beta-cell functions. TopIIA and GADA are suggested to be better markers for Taiwanese TIDM patients because of their higher prevalence and persistence. (C) 2004 Elsevier Inc. All rights reserved.