Type 1 diabetes is much less common than type 2 diabetes and typically affects younger individuals. Type 1 diabetes usually begins before age 40, although there have been people diagnosed at an older age. In the United States, the peak age at diagnosis is around 14. Type 1 diabetes is associated with deficiency (or lack) of insulin. It is not known why, but the pancreatic islet cells quit producing insulin in the quantities needed to maintain a normal blood glucose level. Without sufficient insulin, the blood glucose rises to levels which can cause some of the common symptoms of hyperglycemia. These individuals seek medical help when these symptoms arise, but they often will experience weight loss developing over several days associated with the onset of their diabetes. The onset of these first symptoms may be fairly abrupt or more gradual.
To learn more about type 1 diabetes basics, see our type 1 diabetes slideshow.
It has been estimated that the yearly incidence of type 1 diabetes developing is 3.7 to 20 per 100,000. More than 700,000 Americans have this type of diabetes. This is about 10% of all Americans diagnosed with diabetes; the other 90% have type 2 diabetes.
In the case of type 1 diabetes, the islet cells of the pancreas that produce insulin are seen as the "enemy" by mistake. The body then creates antibodies to fight the "foreign" tissue and destroys the islet cells' ability to produce insulin.
The lack of sufficient insulin thereby results in diabetes. It is unknown why this autoimmune diabetes develops. Most often it is a genetic tendency. Sometimes it follows a viral infection such as mumps, rubella, cytomegalovirus, measles, influenza, encephalitis, polio, or Epstein-Barr virus.
Certain people are more genetically prone to this happening although why this occurs is not know. In some cases, family members of those with type 1 diabetes also have a family history of autoimmine conditions. Thus, 2 people may be infected with the same virus and only one of them who is genetically prone will go on to develop diabetes.
Other less common (very rare) causes of type 1 diabetes include injury to the pancreas from toxins, trauma, or after the surgical removal of the majority (or all) of the pancreas.
Type 1 diabetes tends to have less tendency to have other family members affected with diabetes than type 2 diabetes. In the first large family study of diabetes, less than 4% of parents and 6% of siblings of a person with diabetes also had diabetes.
In studies with identical twins, less than 50% of the siblings of a person with diabetes also had diabetes versus almost 100% of siblings of people with type 2 diabetes. Children of fathers with type 1 diabetes are more likely to develop type 1 diabetes than children of mothers with type 1 diabetes.
Type 1 diabetes must be treated with insulin. This involves injecting insulin under the skin—in the fat—for it to get absorbed into the bloodstream where it can then access all the cells of the body that require it. Insulin cannot be taken as a pill because the juices in the stomach would destroy the insulin before it could work. Remember, insulin is a hormone, and like all other hormones, insulin is a protein and therefore it has a very important 3-dimensional structure which is destroyed by the acid in the stomach. Even if it did make it through the stomach, the digestive enzymes secreted by the digestive part of the pancreas would digest the insulin protein molecule. Scientists are looking for new ways to give insulin. Inhaled insulin is available for use, but it requires lung testing before and during its use to be sure it will work properly. It is typically given with meals. The individual must still take long-acting insulin as an injection. But today, shots are the most widely used method. Insulin pumps have become more popular. Most insurance companies will cover some of the cost, but it can be an expensive alternative to injections depending on insurance coverage. While there is one tubeless pump available in the United States, there are new tubeless options being developed and launched in other countries.