Improving diagnostic accuracy of 3 Screen ICA ELISA kit in the identification of Japanese type 1 diabetes

AIM/INTRODUCTION: This study aimed to investigate the clinical utility of 3 Screen ICA ELISA in identifying immune‐mediated type 1 diabetes in Japanese subjects. METHODS: We compared the positivity of 3 Screen ICA were compared with autoantibodies against GAD, IA‐2, and ZnT8 in 638 patients with type 1 diabetes and 159 healthy control subjects. RESULTS: With a cut‐off value of 20.0 index, 67.4% of acute‐onset type 1 diabetic patients, 71.8% of slowly progressive type 1 diabetic (SPIDDM) patients, and none of the fulminant type 1 diabetic patients showed 3 Screen ICA levels above this threshold. The prevalence of 3 Screen ICA was 14.2% higher in acute‐onset type 1 diabetes and 1.6% higher in SPIDDM than in GADA. 3 Screen ICA‐positive cases were found in 4.8% of cases of individual autoantibody‐negative acute‐onset type 1 diabetes and 3.8% of SPIDDM, indicating improved diagnostic sensitivity with the 3 Screen ICA. Among individual autoantibody‐negative patients, the sum of each autoantibody level was significantly lower in fulminant type 1 diabetes than in acute onset type 1 diabetes and in SPIDDM (P < 0.0001). Additionally, 84.2% of patients negative for individual autoantibodies but positive for 3 Screen ICA had a sum of individual autoantibody levels of ≥4.7 U/mL. Furthermore, 3 Screen ICA levels were significantly higher in patients with type 1 diabetes with other autoimmune diseases than in those without (P < 0.0001). CONCLUSION: Our findings suggest that the 3 Screen ICA ELISA may be a valuable screening tool for Japanese patients with type 1 diabetes, potentially increasing the diagnostic sensitivity and accuracy beyond the existing GADA, IA‐2A, and ZnT8A tests.