The aim of this study was to evaluate the prevalence and clinical significance of antibodies to glutamic acid decarboxylase (anti-GAD) in 103 diabetic patients with secondary failure of sulfonylurea agents (SU-F).
The percentage of anti-GAD positive cases among the SU-F patients was 28.2%.
The mean interval (8.9 years) between the discovery of diabetes and the institution of insulin therapy in the patients with anti-GAD antibody was shorter (p<0.05) than in the patients without anti-GAD antibody (12.1 years). The mean body mass index (21.1 kg/m²) of the anti-GAD-positive patients was lower (p<0.05) than that of the anti-GAD-negative patients (23.1 kg/m²). The mean urinary C-peptide excretion of the anti-GADpositive patients was lower than that of the anti-GAD-negative patients (29 rig/day vs. 65 fig/day, p<0.05), and the insulin dose then required was higher (0.67 U/kg/day vs.0.37 U/kg/day, p<0.05).
In conclusion, nearly 30% of DM-SF patients were anti-GAD-antibody-positive, suggesting that an autoimmune mechanism may play an important role in the pathogenesis in some diabetic patients with secondary failure of sulfonylurea agents. Patients who appear to have type 2 diabetes should be examined carefully by determining whether they are positive for autoantibody to GAD.