Autoantibodies to GAD and IA-2 in Saudi Arabian diabetic patients

Aims To determine the prevalence of autoantibodies in sera of Saudi diabetic patients including Type 1 and Type 2 diabetes mellitus (DM) and gestational diabetes mellitus (GDM) living in Jeddah, Saudi Arabia. Apart from data on the prevalence of islet-cell antibodies in patients in Ryhadh (Al-Attas et al. Freqency of islet cell antibodies in adult newly diagnosed diabetic patients. Ann Saudi Med 1990; 10: 369-373) immunological markers of autoimmune diabetes have not been explored in Saudi Arabians. Methods Autoantibodies to GAD65 (GADA) and IA-2 (IA-2A) were determined using radio-immunoprecipitation assays. Results In Type 1 DM patients, 54% were GADA(+) and 27% were IA-2A(+). A greater negative effect of disease duration was noted for IA-2A than for GADA positivity. Autoantibodies were more prevalent with younger age of onset. GADA were slightly more common in female Type 1 DM patients. In Type 2 DM, 8/99 patients were GADA(+), and three of these patients with shorter disease duration were also IA-2A(+). GADA, and particularly IA-2A, were associated with a younger age of onset of Type 2 DM and all the autoantibody-positive Type 2 DM patients were insulin-treated. GADA were detected in 2.2% of GDM patients, but none of these patients possessed IA-2A. Conclusions The prevalence and associations of autoantibodies in Saudi diabetic patients are very similar to those reported for diabetic patients in other ethnic groups.