Flowcharts of frequencies of autoantibodies, masked GAD65Ab(DPD), and β-cell functional reserve. A, KPD patients were categorized into subgroups of patients with and without preserved β-cell functional reserve (n = 144 and 100, respectively). Frequencies of masked GAD65Ab(DPD) are compared in both groups. Patients in the β-cell function-negative subgroup had significantly lower frequency of masked GAD65Ab(DPD) (59%) compared with the frequency in patients with preserved β-cell functional reserve (78%) (P = .002). B, KPD patients were categorized into subgroups of patients with and without autoantibodies (n = 83 and 161, respectively). Frequencies of masked GAD65Ab(DPD) are compared in both groups. Patients in the autoantibody-negative subgroup had significantly higher frequency of masked GAD65Ab(DPD) (80%) compared with the frequency in autoantibody-positive patients (49%) (P < .0001). Among autoantibody-positive patients with masked GAD65Ab(DPD), the frequency of patients with preserved β-cell functional reserve was significantly higher compared with that in patients without masked GAD65Ab(DPD) (41% and 21%, respectively; P = .04).