Type 1 diabetes
Type 1 diabetes (T1D) results from a lack of the hormone insulin, which is required to control the concentrations of glucose in the body.
Insulin acts on cells to increase their uptake and breakdown of glucose and to decrease the output of glucose made in the liver.
What happens in type 1 diabetes?
T1D, previously known as juvenile or early-onset diabetes, is an autoimmune disease in which the body’s immune system destroys the cells that produce insulin. These cells, called beta cells, are located together in ‘islets’ scattered throughout the pancreas.
The immune response against the beta cells can be detected by the presence of ‘islet autoantibodies’ in the blood against beta-cell proteins, including to insulin itself. These antibodies appear in the first few years of life in most children who will develop the disease. Testing for them to diagnose early, pre-clinical T1D is now possible and opens the way for therapeutic intervention before most of the beta cells have been destroyed - in the hope of preventing insulin deficiency, high blood sugar levels and symptoms.
In about 40 per cent of cases, T1D is diagnosed after the age of 18, often with less dramatic symptoms and may initially be mistaken for T2D. The presence of islet autoantibodies establishes the diagnosis of T1D in these cases.
Diabetes, genetics and lifestyle
Traditionally, T1D was considered to be solely a genetic disease, and T2D a ‘lifestyle’ disease associated with obesity. However, the environmental factors driving the epidemic of T2D also impact T1D, the incidence of which has more than trebled since the middle of the 20th century.
Environmental factors have increased the effect (‘penetrance’) of genes that predispose T1D. Understanding how the environment acts on genes (an area called ‘epigenetics’) to then alter immune function and destroy beta cells is critical to decrease the incidence of T1D.
Treating type 1 diabetes
Although less common than T2D, T1D can be more severe and requires daily treatment with insulin injections.
Currently, there is no preventative measure or cure for T1D. People with T1D are dependent for the rest of their lives on regular injections of insulin to control their blood glucose levels.
Insulin lets people manage their diabetes, but the control of blood glucose is never perfect, pre-disposing to complications in the longer term.