Progress in the characterization of slowly progressive autoimmune diabetes in adult patients (LADA or type 1.5 diabetes).

LADA or type 1.5 diabetes is a slowly progressive form of autoimmune diabetes of adults and represents a considerable proportion (about 5-10%) of all diabetic patients. Associations with high risk HLA genotypes and autoimmune phenomena (GAD, IA2, ICA) show similarities with type 1 diabetes, but phenotypical characteristics of these patients do not allow the correct identification without screening of GAD antibodies. The relatively low antibody titers against islet-cell antigens in LADA patients may be sign of a less aggressive form of autoimmune diabetes and could be responsible for the long non-insulin requirement phase of this diabetes type. Similar as in prediabetic relatives of type 1 diabetic patients the risk for beta cell failure in adult "type 2 diabetic" patients increases with the number of antibodies positive. Consequently, low titers of GAD--in particular in elderly patients--do not predict a progressive and rapid loss of beta-cell failure, when associations with high risk genotypes or other islet-cell antibodies are lacking. Patients with LADA share insulin resistance with type 2 diabetic patients, but display a more severe defect in stimulated beta-cell capacity than patients with classical type 2 diabetes. With respect to features of the metabolic syndrome, patients with LADA have lower BMI, blood pressure and triglyceride levels compared with classical type 2 diabetes patients. Early identification of LADA patients will be mandatory, when effective immune interventions are available for prevention of the beta-cell destructive process and insulin requirement of these patients.