Objective: To investigate the relationship between latent autoimmune diabetes in adults (LADA) and thyroid autoimmunity.
Methods: The frequency of thyroid peroxidase antibody (TPO-Ab) and thyroglobulin antibody (TG-Ab) was determined with radioimmunoassay in 394 subjects, including 90 LADA, 104 classic type 1 diabetics (T1DM), 100 type 2 diabetics (T2DM) and 100 controls. Glutamic acid decarboxylase antibody (GAD-Ab) was measured with radioligand immunoassay.
Results: (1) TPO-Ab existed more frequently in LADA (16.7%, 15/90) than in T2DM patients (7.0%, 7/100; P < 0.05). The frequency of thyroid antibody (TPO-Ab or TG-Ab positivity) in LADA and T1DM was 18.9% (17/90) and 25.0% (26/104) respectively, being higher than that in the control group (8/100, 8.0%; P < 0.05). (2) Thyroid antibodies occurred more frequently in LADA patients with higher titer of GAD-Ab (GAD-Ab > or = 0.5) than those with lower ones (50.0% vs 12.5%, P < 0.05). (3) 47.1% (8/17) of LADA patients with thyroid autoimmunity had thyroid dysfunction as compared with 17.6% (6/34) in the group without thyroid antibodies (P < 0.05).
Conclusions: (1) LADA patients, especially those with high titer of GAD-Ab, have high risk for thyroid autoimmunity. (2) The presence of thyroid antibody may predict high risk for thyroid dysfunction in LADA patients. (3) LADA may be one of the components in autoimmune polyendocrine syndrome.