Type 1 diabetes (also known as insulin-dependent diabetes mellitus [IDDM] or juvenile or childhood diabetes) occurs when the pancreas doesn't make enough insulin. When there is not enough insulin, or when the insulin is not working correctly (as in Type 2 diabetes), the level of sugar in the blood can be high because insulin transports sugar from the blood into cells. The resulting condition is called diabetes. Since insulin is not created sufficiently, patients with Type 1 diabetes must take insulin injections throughout their lifetime to regulate their blood sugar levels.
What Is Insulin?
Insulin is a hormone made in the pancreas, an organ inside the abdomen. Special cells called "beta cells" make the insulin. These cells are located in a part of the pancreas called the "islets" (pronounced eye-lets). When a person has Type 1 diabetes, there is a loss of these specialized cells that make insulin. Roughly three months after diagnosis, there is a "honeymoon" period during which people may need very little insulin. Unfortunately, insulin production is reduced an additional 30 percent in each of the following two years. This is the most likely due to autoimmune destruction of the islets where insulin is made. Many people with Type 1 diabetes continue to make small amounts of insulin for many years. The ability to continue to produce some insulin is believed to help prevent both acute and chronic complications of diabetes.
Functions of Insulin
A first function of insulin is to allow sugar to pass into our cells so that it can be "burned" for energy. The cells are like a furnace that burns fuel to make energy. Our bodies constantly need energy for all of our body functions, such as allowing our hearts to beat and our lungs to breathe. Sugar comes from two places: "Internal" sugar comes from the body's own ongoing production in the liver or from the release of stored sugar from the liver. This sugar is released into the bloodstream. "External" sugar comes from the food we eat. It enters the stomach and then moves into the intestine where it is absorbed. When people do not have diabetes, the pancreas makes insulin to allow both internal and external sugar to move into the body's cells. With Type 1 diabetes, adequate insulin is not available and the sugar builds up in the bloodstream and spills into the urine.
A second function of insulin is to shut off the body's "internal" production of sugar. Internal sugar comes mostly from the liver. When the insulin level is too low, internal sugar is made in excess by the liver. There is not enough insulin to "turn off" the liver's sugar production and blood sugar levels rise.
Currently, many people who develop Type 1 diabetes, or who have had it for a period of time, are overweight or obese. This results in insulin resistance (which is typically found in people with Type 2 diabetes) and may result in increased insulin needs.
Because mortality from diabetes has declined in recent decades, resulting in a longer lifespan, there are now more adults living with Type 1 diabetes in comparison to children.