Factors associated with GAD antibody titer in subtypes of type 1 diabetes

Objective: The objective of this study was to compare factors associated with glutamic decarboxylase antibody (GADAb) titer between acute-onset and slowly progressive type 1 diabetes. Research design and methods: We used a cross-sectional study to investigate 90 cases of GADAb-positive type 1 diabetes, including 40 acute-onset and 50 slowly progressive cases, to clarify factors associated with GADAb positivity in the two disease subtypes. We performed multivariate linear regression analysis to clarify factors associated with GADAb titer. Results: In acute-onset cases, positive insulinoma-associated antigen-2 antibody (IA-2Ab) was negatively correlated with GADAb titer (β = −1.29, p = 0.048). In slowly progressive cases, GADAb titer was positively correlated with age (β = 0.05, p = 0.035) and positive thyroid autoantibodies (β = 1.59, p = 0.023), and negatively correlated with duration of diabetes (β = −1.34, p = 0.003). In slowly progressive cases, female gender (β = 1.65, p = 0.009) and age (β = 0.05, p = 0.048) were positively correlated, and duration of diabetes (β = −1.34, p = 0.004) and IA-2Ab positivity (β = −1.92, p = 0.029) were negatively correlated with GADAb titer only in cases with high GADAb titer. Conclusions: GADAb titer was associated with autoimmune activity of pancreatic beta cells in acute-onset and slowly progressive cases with high GADAb titer, and duration of diabetes in slowly progressive cases.