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Type 1 diabetes: An introduction

Diabetes is a group of diseases that occur when the body can't produce insulin or process it properly. As a result, too much sugar stays in the blood. Over time, this can lead to a variety of serious complications including heart disease, kidney failure and blindness.

Type 1 and type 2 diabetes account for nearly all cases of this disease. But according to the Centers for Disease Control and Prevention (CDC), only about 5% to 10% of the people with diabetes have type 1.

Type 1 diabetes: A lack of insulin

Type 1 diabetes happens when the body produces no or very little insulin—a hormone that transports glucose (sugar) from the blood to the cells where it is used for fuel. As a result, unused glucose builds up in the blood.

This shortage or complete absence of insulin happens because the pancreas, which produces insulin, is attacked by the body's own immune system. The immune system destroys the specific cells in the pancreas that produce insulin.

The exact cause of type 1 diabetes isn't known, according to CDC. Certain genes confer an increased risk of developing the disease, and it's also thought that exposure to unidentified environmental triggers, such as viruses, causes the body to attack itself.

Type 1 diabetes usually develops in children and young adults, but it can occur at any age, according to CDC. It's more common among whites than other racial groups. There is no known way to prevent type 1 diabetes.

Quick onset of symptoms

Type 1 diabetes doesn't always cause symptoms. According to CDC and the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), symptoms of type 1 diabetes may include:

  • Excessive thirst.
  • Frequent urination.
  • Extreme hunger.
  • Weight loss.
  • Blurred vision.
  • Extreme fatigue.

Nausea, vomiting or stomach pain may accompany these symptoms.

If you have symptoms of diabetes, see your doctor. A blood test can check for the disease.


According to the NIDDK, the complications of diabetes can affect many parts of the body.

These complications include:

  • Cardiovascular problems, including heart disease, heart attack and stroke.
  • Loss of vision and blindness.
  • Kidney failure.
  • Nerve damage, which can cause pain or numbness in your feet, hands and limbs.
  • Impaired circulation to the feet, which can cause wounds to heal slowly or become infected. In severe cases, a foot wound that doesn't heal may end up leading to amputation.

Blood sugar that's too high can lead to a condition called diabetic ketoacidosis (DKA). This is a life-threatening situation. The signs include vomiting, nausea, shortness of breath and a fruity smell on the breath. If untreated, DKA can lead to a coma or death.

Blood sugar that's too low can also be dangerous and cause unconsciousness.

Controlling the disease

People with type 1 diabetes must take insulin each day in order to live, according to CDC. Insulin can be delivered by injection or with an insulin pump.

The amount of insulin you use is determined by how much food you eat and how active you are. You'll need to check your blood sugar frequently to make sure you're getting the right balance.

Some people with type 1 diabetes can benefit from a fully automated system called an artificial pancreas. An artificial pancreas system has three main components: a sensor to read blood glucose levels and send data to a computer; an insulin pump or other delivery mechanism; and the computer that runs the show. The goal is to reduce or eliminate the need for individuals to carry out these steps manually several times a day.

For some people with type 1 diabetes who have trouble maintaining a healthy blood sugar level, pancreatic islet therapy may be an option. Pancreatic islets are groups of cells, including the cells that produce insulin in a healthy pancreas. Transplanted pancreatic islets allow many people with type 1 diabetes to produce their own insulin.

In some cases, the islet cell therapy allows people to stop injecting insulin. But the procedure needed to infuse the islet cells has risks. And the treatment requires people to take medicines to suppress their immune system, which may have serious side effects. Scientists are working to improve options for islet cell therapy. But so far, the effects of the treatment are not permanent.

Beyond insulin

According to the NIDDK, treatment for type 1 diabetes also includes:

  • Following a healthy meal plan.
  • Being physically active.
  • Controlling blood pressure and cholesterol.

Work closely with your healthcare team. You'll need regular checkups to measure your average blood glucose, your blood pressure, your cholesterol and the health of your eyes, among other things.

Learn more

For more information, visit the Diabetes health topic center.

Reviewed 6/30/2023

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