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Type 1 Diabetes Causes

What leads to the development of type 1 diabetes?

It isn’t entirely clear what triggers the development of type 1 diabetes. Researchers do know that genes play a role; there is an inherited susceptibility. However, something must set off the immune system, causing it to turn against itself and leading to the development of type 1 diabetes.

Genes Play a Role in Type 1 Diabetes
Some people cannot develop type 1 diabetes; that’s because they don’t have the genetic coding that researchers have linked to type 1 diabetes. Scientists have figured out that type 1 diabetes can develop in people who have a particular HLA complex. HLA stands for human leukocyte antigen, and antigens function is to trigger an immune response in the body.

There are several HLA complexes that are associated with type 1 diabetes, and all of them are on chromosome 6.

Different HLA complexes can lead to the development of other autoimmune disorders, such as rheumatoid arthritis, ankylosing spondylitis, or juvenile rheumatoid arthritis. Like those conditions, type 1 diabetes has to be triggered by something—usually a viral infection.

What Can Trigger Type 1 Diabetes
Here’s the whole process of what happens with a viral infection: When a virus invades the body, the immune system starts to produce antibodies that fight the infection. T cells are in charge of making the antibodies, and then they also help in fighting the virus.

However, if the virus has some of the same antigens as the beta cells—the cells that make insulin in the pancreas—then the T cells can actually turn against the beta cells. The T cell products (antibodies) can destroy the beta cells, and once all the beta cells in your body have been destroyed, you can’t produce enough insulin.

It takes a long time (usually several years) for the T cells to destroy the majority of the beta cells, but that original viral infection is what is thought to trigger the development of type 1 diabetes.

Not every virus can trigger the T cells to turn against the beta cells. The virus must have antigens that are similar enough to the antigens in beta cells, and those viruses include:

  • B4 strain of the coxsackie B virus (which can cause a range of illnesses from gastrointestinal problems to myocarditis—inflammation of the muscle part of the heart)
  • German measles
  • Mumps
  • Rotavirus (which generally causes diarrhea)

There have also been some controversial studies into the connection between drinking cow’s milk as an infant and the development of type 1 diabetes. Researchers don’t all agree on this, but some believe that the proteins in cow’s milk are similar to a protein that controls T cell production called glycodelin1. The baby’s body attacks the foreign protein—the cow’s milk protein—but then also attacks glycodelin, leading to an overproduction of T cells. And too many T cells in the body can lead to those T cells destroying the beta cells.

Researchers have made significant progress in understanding the cause of type 1 diabetes, and they’re still hard at work to figure out why certain viruses trigger it and why T cells turn against beta cells. The medical community wants to better understand the cases of diabetes in order to prevent it.

1. Vaarala O, Knip M, Paronen J, Hamalainen AM, Muona P, Vaatainen M, Ilonen J, Simell O, Akerblom HK.  Cow's milk formula feeding induces primary immunization to insulin in infants at genetic risk for type 1 diabetes.  Diabetes.  1999 Jul;48(7):1389-94.

American Diabetes Association.  Standards of Medical Care in Diabetes—2009. Diabetes Care. 2009;32:S13-61.

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Type 1 Diabetes Risk Factors