Thyroid, gastric, and adrenal autoimmunities associated with insulin-dependent diabetes mellitus.

Thyroid microsomal, gastric parietal, and adrenocortical autoantibodies were sought in 1456 Caucasian and 240 black patients with insulin-dependent diabetes mellitus (IDDM), in 1467 of the Caucasian patients' immediate family members, and in 1519 normal Caucasian control subjects. Positive clinical significances and predictive values of these autoantibodies for associated gland dysfunctions were found. In all groups, thyroid and gastric autoantibodies were more common in female subjects. In the control group, thyroid and gastric autoantibodies were more frequent with advancing age, affecting more than one-third of Caucasian women after age 60 yr. This age-augmented increase occurred very prematurely in patients with IDDM and their relatives. Among the patients with IDDM and thyroid and gastric autoantibodies, these autoantibodies appeared by the time of onset of IDDM in the large majority of cases; however, they were more common among patients with later ages of onset of IDDM. Occurrence of thyroid and gastric autoantibodies in 404 siblings of patients with IDDM was not affected by their degree of HLA-haplotype sharing with their diabetic sibling, suggesting that the inherited predisposition to thyroid and gastric autoimmunity is not HLA-related. In light of this, the increased frequencies of these antibodies in patients with IDDM and their relatives suggest that "thyroid and gastric autoimmunity genes" may also predispose to IDDM.