Diabetes: Type 1 Diabetes
Type 1 diabetes occurs when the body's own immune system destroys the
insulin-producing cells of the pancreas (called beta cells).
Normally, the body's immune system fights off foreign invaders like viruses or bacteria. But for unknown reasons, in people with type 1 diabetes, the immune system attacks various cells in the body. This results in a complete deficiency of the insulin hormone.
Some people develop a type of diabetes - called secondary diabetes -- which
is similar to type 1 diabetes, but the beta cells are not destroyed by the
immune system but by some other factor, such as
cystic fibrosis or pancreatic
Normally, the hormone insulin is always secreted by the pancreas in low
amounts. When you eat a meal, food stimulates an increase in the amounts of
insulin released from the pancreas. The amount that is released is proportional
to the amount that is required by the size of that particular meal.
So what does insulin do? Insulin's main role in the body is to help move
certain nutrients -- especially a sugar called glucose -- into the cells of the
body's tissues. Cells use sugars and other nutrients from meals as a source of
energy to run a variety of important processes for the body.
When glucose is moved into cells, the amount of sugar in the blood decreases.
Normally that signals the beta cells in the pancreas to stop secreting insulin
so that you don't develop low blood sugar levels (hypoglycemia).
But the destruction of the beta cells that occurs with type 1 diabetes throws
the entire process into disarray.
In people with type 1 diabetes, glucose isn't moved into the cells because
insulin is not available. When glucose builds up in the blood instead of going
into cells, the body's cells starve for nutrients and other systems in the body
must provide energy for many important bodily functions. As a result, high blood
glucose develops and can cause:
- Dehydration. The
build up of sugar in the blood can cause an increase in urination (to try to
clear the sugar from the body). When the kidneys lose the glucose through
the urine, a large amount of water is also lost, causing dehydration.
- Weight loss. The loss of sugar in the urine means a loss of
calories which provide energy and therefore many people with high sugars
lose weight. (Dehydration also contributes to weight loss.)
- Diabetic ketoacidosis (DKA). Without insulin and because the cells
are starved of energy, the body breaks down fat cells. One of the products
of fat break down is a specific type of acid that can be used by the brain
for energy. Unfortunately none of the body's other cells can use this acid
for energy, and thus continue to starve without insulin. So, the liver
releases the sugar it stores to help out. Since the body cannot use these
sugars without insulin, more sugars piles into the blood stream. The
combination of high excess sugars, dehydration and acid build up is known as
"ketoacidosis" and can be life-threatening if not treated immediately.
- Damage to the body. Over time, the high glucose levels in the blood
may damage the nerves and small blood vessels of the eyes, kidneys, and
heart and predispose a person to atherosclerosis (hardening) of the large
arteries that can cause heart
attack and stroke.
Who Gets Type 1 Diabetes?
Although the disease usually starts in people under the age of 20,
type 1 diabetes may occur at any age.
The disease is relatively uncommon, affecting 1 in 250 Americans. The
condition is more common in whites than in blacks and occurs equally in men and
What Causes Type 1 Diabetes?
Doctors don't know all the factors that lead to type 1 diabetes.
Clearly, the susceptibility to the condition can be inherited.