RESUMO
BACKGROUND: Pancreatic cell destruction causing type 1 diabetes is associated to diverse autoantibodies. Antibodies against glutamic acid decarboxylase have been found in type 1 (DM1) and type 2 diabetic patients (DM2). Their presence in siblings is unknown. OBJECTIVE: To determine the presence of anti-GAD65 autoantibodies in diabetic patients and their siblings. PARTICIPANTS AND METHOD: Sixty-eight individuals were included and distributed in four groups: group 1 DM1, group 2 DM2, group 3 and 4 healthy siblings of patients from groups 1 and 2. Anti-GAD65, peptide C, serum glucose, total cholesterol and triglycerides were obtained. Body mass index and hip-waist ratio were measured. RESULTS: Anti-GAD65 antibodies were positive in 23% of DM1, in 14% of DM2, and in 7.7% and 9.5% in siblings of both groups, respectively. Using Mann-Whitney's U the mean of anti-GAD65 in diabetic type 1 and 2 patients was p = 0.022; between DM1 and their siblings and between DM2 and their siblings there was no statistical significance. C peptide was low in cases of positive anti-GAD65 of DM1 and DM2; and it was normal in patients with negative anti-GAD65. CONCLUSIONS: Anti-GAD65 autoantibodies are more frequent in type 1 diabetic patients. There were no meaningful differences regarding the presence of anti-GAD65 in patients and their siblings.