The Physiology of Type 1 Diabetes
Understanding the mechanics of what causes Type 1 diabetes helps a person understand the basics of the disease, its effects, and even how it differs from other similar diseases.
How It Begins
Although no one is sure exactly what triggers the body to develop Type 1 diabetes, science and research have come a long way in getting closer to that point. Some aspects of the disease are understood, while others are still being studied.
Research has shown that the body of a person who develops Type 1 diabetes “turns against itself.” The T cells of the immune system become confused and attack the body instead of protecting it. For reasons still not completely understood, the T cells attack the pancreas's beta cells, located within the Islets of Langerhans. These beta cells produce insulin to help convert food into fuel.
Until 1997, this type of diabetes was called juvenile diabetes, since it almost always affects children. But with the discovery that this disease also affects adults in rare cases, its name was changed to Type 1 diabetes.
Scientists are still trying to figure out the exact cause for the T cells' confusion. Current speculation is that a combination of a genetic irregularity and some sort of environmental trigger must be present; however, a person can have that genetic irregularity and never develop Type 1 diabetes.
The onset can be as slow as a few years or as quick as a few months. Oftentimes, parents report their child had another type of trauma—the flu, another sickness, or even an injury—at the time of onset. Although certain sicknesses or injuries can occur just before a diagnosis of Type 1 diabetes, they are not the cause of the illness. Rather, the strain of those events may have helped stimulate the onset of diabetes.
Even though it is always beneficial to catch a disease early, it is not yet possible to stop the onset of diabetes. (See Chapter 21 for details on research toward that goal.)
As the body develops the autoimmunity, and the T cells attack and damage or destroy the islet cells, the body slowly begins to lose its ability to process food into fuel. That's because the insulin produced by these cells is the link between the body's fuel (glucose from food) and the cells. Insulin tells the body to use glucose for fuel. Without insulin, the body doesn't receive the clues that it's time to process food into fuel.
As the insulin-producing cells (the beta cells) within the Islets of Langerhans begin to die, the pancreas does not make enough insulin to store glucose properly. The person's blood sugar rises, and she begins to urinate more often as the glucose forces her body to produce more urine. The increased loss of urine causes dehydration, which she senses as increased thirst. As diabetes progresses, the insulin shortage becomes more severe, and the body goes into starvation mode. This starvation mode causes the body to break down fat for energy, which causes a by-product called ketones to build up. At this point, a scary metabolic crisis can occur, termed diabetic ketoacidosis or DKA. (See Chapter 5 for a detailed explanation of ketones.)
A great book to illustrate this autoimmunity to children and adults is It's Time to Learn about Diabetes, a workbook written by Jean Betschart-Roemer and published by John Wiley & Sons. This book's simple analogies help explain the process in terms that are easy for anyone to grasp.