Autoantibodies to pancreatic beta cell antigens are important serological markers of type 1 diabetes mellitus. The antigens recognised by these autoantibodies include insulin, glutamic acid decarboxylase (GAD65 kDa isoform) and an islet cell antigen named IA-2 or ICA-512. 2 Screen ELISA allows simultaneous measurement of GAD and IA- 2 autoantibodies in the same sample.