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; rather, they are destroyed by some other factor, such as cystic
fibrosis or pancreatic surgery.
Understanding Insulin and Type 1 Diabetes
Normally, the hormone insulin is secreted by the pancreas in low amounts. When you eat a meal, sugar (glucose) from
food stimulates the pancreas to release insulin. The amount that is released is proportional to the amount that is
required by the size of that particular meal.
Insulin’s main role is to help move certain nutrients — especially sugar — into the cells of the body’s tissues.
Cells use sugars and other nutrients from meals as a source of energy to function.
The amount of sugar in the blood decreases once it enters the cells. Normally, that signals the beta cells in the
pancreas to lower the amount of insulin secreted 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, sugar isn’t moved into the cells, because insulin is not available. When sugar
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 sugar develops and can
The buildup 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
The loss of sugar in the urine means a loss of calories; 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. Products of this fat breakdown include acidic chemicals called ketones that can be used for energy.
Levels of these ketones begin to build up in the blood, causing an increased acidity. The liver continues to release
the sugar it stores to help out. Because the body cannot use these sugars without insulin, more sugar piles into the
bloodstream. The combination of high excess sugars, dehydration, and acid buildup is known as “ketoacidosis” and can
be life-threatening if not treated immediately.
Damage to the body.
Over time, the high sugar 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 age 20, type 1 diabetes may occur at any age.
The disease is relatively uncommon, accounting for only about 5% of people with diabetes. The condition is more
common in whites than in blacks and occurs equally in men and women.
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
Doctors have identified that an environmental trigger plays a role in causing the disease. Type 1 diabetes appears
to occur when something in the environment — a toxin or a virus (but doctors aren’t sure) — triggers the immune
system to mistakenly attack the pancreas and destroy the beta cells of the pancreas to the point where they can no
longer produce sufficient insulin. Markers of this destruction — called autoantibodies — can be seen in most people
with type 1 diabetes. In fact, they are present in 85% to 90% of people with the condition when the blood sugars are
Because it’s an autoimmune disease, type 1 diabetes can occur along with other autoimmune diseases such as
hyperthyroidism from Grave’s disease or the patchy decrease in skin pigmentation that occurs with vitiligo.
What Are the Symptoms of Type 1 Diabetes?
The symptoms of type 1 diabetes are often subtle, but they can become severe. They include:
- Increased thirst
- Increased hunger (especially after eating)
- Dry mouth
- Nausea and occasionally vomiting
- Abdominal pain
- Frequent urination
- Unexplained weight loss (even though you are eating and feel hungry)
- Fatigue (weak, tired feeling)
- Blurred vision
- Heavy, labored breathing (Kussmaul respiration)
- Frequent infections of the skin, urinary tract, or vagina
Signs of an emergency with type 1 diabetes include:
- Shaking and confusion
- Rapid breathing
- Fruity smell to the breath
- Abdominal pain
- Loss of consciousness (rare)
How Is Type 1 Diabetes Diagnosed?
If your health care provider suspects type 1 diabetes, he will first check for abnormalities in your blood (high
blood sugar level). In addition, he may look for glucose or ketone bodies in the urine.
Consequences of Uncontrolled Type 1 Diabetes
When type 1 diabetes isn’t well controlled, a number of serious or life-threatening problems may develop,
This eye problem occurs in about 80% of adults who have had type 1 diabetes for more than 15
years. Diabetic retinopathy in type 1 diabetes is extremely rare before puberty no matter how long someone may have
had the disease. Medical conditions such as good control of sugars, management of high blood pressure, and regulation
of blood fats like cholesterol and triglycerides are important to prevent retinopathy. Fortunately, the vision loss
can be prevented in most people with the condition.
About 20% to 30% of people with type 1 diabetes develop kidney damage, a condition called
nephropathy. The risk for kidney disease increases over time and becomes evident 15 to 25 years after the onset of the
disease. This complication carries significant risk of serious illness — such as kidney failure and heart
Poor blood circulation and nerve damage.
Damage to nerves and hardening of the arteries leads to decreased
sensation and poor blood circulation in the feet. This can lead to increased risk of injury and decreased ability to
heal open sores and wounds, which in turn significantly raises the risk of amputation. Damage to nerves may also lead
to digestive problems such as nausea, vomiting, and diarrhea.