GAD1 and diabetes mellitus: If the titers by ELISA are high (> 10,000 IU/ml), are diagnostic for a true GAD-SD conferring specificity for an autoimmune neurological disease within the GAD-SD; lower titers (< 10,000 IU/ml) are connected with an atypical or nonspecific neurological disease that may require further investigation, whereas very low titers (< 2,000 IU) are typically seen in diabetes or are of unclear significance.