Presence of Anti-Pituitary Antibodies and GAD Antibodies in NIDDM and IDDM

OBJECTIVE To evaluate the clinical significance of the presence of anti-pituitary antibodies (APAs) in patients with NIDDM or IDDM and to examine the relationship of APAs to GAD antibodies (GADAs). RESEARCH DESIGN AND METHODS Serum samples were obtained from patients with NIDDM and IDDM. APAs, determined by Western blot analysis, and GADAs, determined by radioimmunoassay, were detected in the patients' sera and control sera. Urinary levels of C-peptide (U-CPR) were measured. RESULTS The prevalence of APAs was significantly higher in patients with NIDDM (24.2%) or IDDM (56.8%) than in healthy control subjects (6%). In patients with NIDDM, the levels of U-CPR were significantly lower, and the prevalence of insulin deficiency was higher in APA+ patients than in APA− patients. CONCLUSIONS This is the first study to demonstrate that the prevalence of APAs is increased in patients with NIDDM and IDDM. The presence of APAs may be related to reduced secretion of insulin in NIDDM patients.