Type 1 diabetes is caused by an absolute insulin deficiency, usually resulting from autoimmune destruction of the insulin-producing beta cells in the pancreas.

Classification

• Type 1a: immune mediated
• Type 1b: non-immune mediated
• Latent autoimmune diabetes in adults (LADA) - slower progression of insulin deficiency
  • It can be suspected in patients who develop diabetes in adult life with associated ketosis, weight loss, low BMI and family history of autoimmune disease.

Epidemiology:

• One of the most common chronic diseases in the UK, prevalence is rising
• in the UK, 4.7 million people have diabetes
• Peak incidence in childhood

Aetiology:

• There may be a genetic component (a heritable disease)
• It is estimated that up to 95% of patients with T1DM have human leucocyte antigens HLA-DR3 or HLA-DR4.
• Environmental factors: diet, reduced vitD exposure, obesity
• It may be triggered by certain viruses, such as the Coxsackie B virus and enterovirus

Pathophysiology

• Autoimmune destruction of insulin producing cells of a genetically predisposed individual
  • Linked to family of autoimmune diseases: Coeliac, pernicious anaemia, Addison’s