Immunopathological and genetic features in slowly progressive insulin-dependent diabetes mellitus and latent autoimmune diabetes in adults.

In 1982 we proposed the presence of a subtype of type 1 diabetes [slowly progressive insulin-dependent diabetes mellitus (SPIDDM)], which was characterized by persistently positive islet cell antibody, late age of onset, noninsulin-dependent diabetes, and slowly progressive beta cell failure. Since then many studies demonstrated that this subtype of type 1 diabetes is prevalent in many ethnic groups and was later called the latent autoimmune diabetes in adults (LADA). Recent epidemiological studies reported that about 10% of patients with apparent type 2 diabetes have at least one autoantibodies against islet-specific antigen with high potential to progress to insulin-dependent state. Between SPIDDM and LADA some differences are reported in terms of some genetic predispositions including HLA class II and class I genes, vitamin D receptor gene, and CTLA4 genes. Common features in SPIDDM and LADA including preserved beta cells at the onset of diabetes and weak T cell response to residual beta cells suggest that these subtypes of type 1 diabetes are suitable candidates for prevention treatment for further progression of beta cell failure.