Predicted age of onset of diabetes. Multiple linear regression was used to evaluate potential predictors of age of diabetes onset, including age at first positive antibody (Ab), initial number of positive antibodies, family history, high-risk HLA-DR3/4, ethnicity, and IAA, GAD, IA-2, and ZnT8 levels (both initial and mean antibody levels). For the first model including initial antibody levels, only initial mIAA levels (loginitialmIAA) and age at first positive antibody (agefirstAb+) were significant predictors of diabetes onset age (A). When analyzing mean antibody levels (B), diabetes onset age was best predicted by mean ECL-IAA levels (logmeanECL-IAA) and age at first positive antibody (agefirstAb+).