Type 1A, or Autoimmune, Diabetes
Although there are several different subtypes of type 1 diabetes, the most common form of type 1 is an autoimmune disease, or an attack from within. For some reason, the T lymphocytes (T cells) don't recognize the beta cells of the pancreas as part of the body, and instead attack them as if they were foreign invaders. The trigger behind this autoimmune siege is not completely understood. Current research points to a combination of environmental and genetic factors.
Signs of Self-Destruction
An antibody is a protein that works along with T cells and other immune system components to destroy a specific foreign presence in the body, such as bacteria or viruses. An autoantibody is an antibody gone haywire — a substance that attacks cells in the body that it is supposed to protect.
Certain diseases that damage the pancreas (e.g., cystic fibrosis, pancreatitis) may cause beta cell destruction that can eventually lead to diabetes and insulin dependence. Some endocrine disorders, including Cushing's syndrome and acromegaly, cause hormone imbalances that trigger insulin resistance and can result in type 2 diabetes.
Up to 90 percent of individuals with type 1 diabetes test positive for the presence of one or more autoantibodies at diagnosis — including islet cell antibodies (ICA), insulin autoantibodies (IAA), and autoantibodies to glutamic acid decarboxylase (a beta cell protein known as GAD). These autoantibodies are associated with the destruction of insulin-producing beta cells. A positive islet cell antibody test can actually detect the autoimmune processes that attack the beta cells of the pancreas before clinical symptoms of hyperglycemia (high blood glucose levels) actually occur.
When type 1 diabetes is known to be caused by an autoimmune process, it is referred to as type 1A diabetes. Immune-mediated type 1 diabetes also puts you at a higher risk for developing other autoimmune disorders, such as celiac disease, thyroid disease, myasthenia gravis, and others.
The autoimmune processes that cause beta cell destruction may happen very quickly, or it may take decades. LADA can be distinguished from type 2 diabetes through blood tests for autoimmune antibodies and c-peptide, a protein that is a by-product of insulin production.
Latent Autoimmune Diabetes in Adults
Yet another subcategory of type 1A diabetes, latent autoimmune diabetes in adults (LADA), occurs in approximately 10 percent of all cases of diabetes of adults over age 30. This immune-mediated form of diabetes is sometimes referred to as late-onset autoimmune diabetes of adulthood, slow-onset type 1, or type 1.5 diabetes. Basically, individuals with LADA experience a slower and longer process of beta cell destruction than do those with type 1A diabetes.