What is type 1 diabetes?

Type 1 diabetes is caused by autoimmune destruction of pancreatic beta-cells resulting in insulin deficiency, consequent hyperglycaemia and a tendency to develop ketoacidosis. The autoimmune aetiology is supported by the presence of autoantibodies specific for pancreatic antigens in the serum of patients with the condition, infiltration of islets with T cells and macrophages (‘insulitis’) and a strong association with specific HLA class II genotypes. The incidence of type 1 diabetes is rising, particularly in the very young. The triggers for this are poorly understood, but there appears to be an interaction between genetic susceptibility and changing environmental factors. It is increasingly recognized that type 1 diabetes can present at any age, but onset in adulthood is associated with a less aggressive disease course and fewer autoimmune markers. The form termed ‘latent autoimmune diabetes of adulthood’ may be clinically indistinguishable from type 2 diabetes at the time of diagnosis, but patients typically need to commence insulin therapy within a few years.