What are the Causes of Type 1 Diabetes?

In type 1 diabetes, the body’s defence system misinterprets the insulin producing cells of the pancreas as foreign invader and starts destroying them. This is known as autoimmune response. Some of the factors that may be responsible for this behaviour of defence system are:

Genetics: Diabetics who inherit certain genes are more at risk of developing type 1 diabetes.
Autoantibodies: These are antibodies prepared by the body against its own cells. In type 1 diabetes, several different auto antibodies are formed against insulin-producing cell proteins. These antibodies are detectable even several years before the onset of the diabetes. These autoantibodies gradually disappear in a few months after the onset of the diabetes.

* Immune markers for type I diabetes are present long before the onset of disease and disappear with the onset of diabetes.

Viruses: Certain viruses have structure similar to an enzyme that is found ininsulin-producing cells. An infection by the virus results in the production of antibodies to this virus. These antibodies may misidentify the enzyme present in the insulin producing cells as the virus and destroy them.

Another theory is that, viral infection alters the structure of surface antigens of the insulin-producing cells. These altered antigens may appear foreign to the immune system and, therefore, the immune system attacks them.

Cow’s Milk: Babies fed on cow’s milk early in life (up to three or four months of age) have more chances of developing type 1diabetes later in life. Children newly diagnosed with type 1 diabetes have high amounts of antibodies that recognize a specific protein in cow’s milk.

If an illness transiently alters the protein on the surface of beta cells similar to protein present in the cow’s milk, the antibodies to the cow milk protein can misinterpret the altered surface proteins of the beta cell as cow milk protein and attack them leading to destruction of the insulin-producing cells of the pancreas.

Free Radicals: Free radicals are formed as a by-product of certain chemical reactions in the body. They cause oxidation in various tissues and thus cause damage. Insulin producing cells of the pancreas have very low levels of the enzymes that break down free radicals. Thus, agents that increase free radical production like smoking, air pollution, faulty diet, etc. can contribute to the formation of excessive amounts of free radicals and can lead to destruction of pancreatic cells.

It is unlikely that either genetics or environmental factors alone cause diabetes. However, if a person inherits a particular set of genes and is exposed to environmental factor, such as a virus or a chemical, then diabetes can develop. It is aptly said – ‘Genetics loads the gun and environment pulls the trigger’.

Type I diabetes is further divided into two types:

Immune-mediated diabetes (Type 1A):
This form of diabetes results from autoimmune destruction of the beta cells of the pancreas.

Idiopathic diabetes (Type I B):
Only a minority of patients with type 1 diabetes fall into this category. This form of diabetes has strong hereditary basis and lacks immunological evidence for autoimmunity. These patients suffer from ketoacidosis frequently.

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