Type 1 Diabetes Mellitus

Alternate Names : Insulin-Dependent Diabetes Mellitus, IDDM, Type 1 Diabetes Mellitus

Overview, Causes, & Risk Factors
Type 1 diabetes mellitus, more commonly known as type 1 diabetes, is a disease in which the pancreas produces too little insulin to meet the body’s needs. Insulin is a hormone that helps control the level of glucose in the blood. Glucose is the main form of sugar in the body.

What is going on in the body?
Glucose is a key source of energy for the cells of the body. When a person eats, the pancreas makes extra insulin to move glucose from the bloodstream to the inside of the cells, where it is converted to energy. A person with type 1 diabetes does not make enough insulin to move the glucose into the cells. As a result, the amount of glucose in the blood becomes too high. This condition is called hyperglycemia, and it can cause damage to the body, if left untreated.

What are the causes and risks of the disease?
The underlying cause of type 1 diabetes is damage to the pancreas caused by the person’s own antibodies. It’s not known why this occurs in some people and not others. Experts believe that it may be caused by an autoimmune disorder. An autoimmune disorder occurs when the body’s immune system produces antibodies against the person’s own tissues. In a person with type 1 diabetes, the antibodies attack the pancreas. The pancreas is a long, thin organ located behind the stomach. As a result, the pancreas can no longer make enough insulin to meet the body’s needs.

Type 1 diabetes accounts for only 5% to 10% of cases of diabetes mellitus diagnosed in the United States. Type 2 diabetes, in which the body cells are resistant to insulin, is much more common.

Experts believe that people with type 1 diabetes have a genetic predisposition to the disease. Then, a trigger activates the disease at some point. Suspected triggers include viruses, environmental factors, and toxins.

Type 1 diabetes is rare in most Asian, African, and American Indian populations but more common in Caucasians. It is also more common in children and in adults younger than 30 years old, but it can appear at any age. It is most often diagnosed in young, thin individuals.

Symptoms & Signs

What are the signs and symptoms of the disease?
The symptoms of type 1 diabetes usually develop over a short amount of time. Symptoms include the following:

  • excessive hunger
  • excessive thirst
  • fatigue and weakness
  • increased amount and frequency of urination
  • infections of the skin, vagina, bladder, or other areas
  • nausea and vomiting
  • visual impairments, such as blurred vision
  • weight loss, despite increased appetite and thirst

If a person with type 1 diabetes goes without enough insulin for too long, the glucose level within the cells can fall dangerously low. When the cells in the body cannot get enough glucose, the body starts to burn fat for energy. This produces waste products known as ketones. High levels of ketones can result in too much acid in the body, called diabetic ketoacidosis. This condition causes:

  • dehydration
  • dry lips
  • sunken eyes
  • labored or deep, rapid breathing
  • vomiting
  • abdominal distress, such as stomach pains or nausea
  • frequent urination
  • drowsiness
  • extreme thirst
  • fruity-smelling breath

Immediate medical attention is needed to prevent coma and death.

Diagnosis & Tests

How is the disease diagnosed?
A medical history and physical exam often lead a doctor to suspect type 1 diabetes. Diabetes is diagnosed on the basis of a high glucose level in the blood.

A blood sample can be measured at a random time or after an 8-hour fast. After an 8-hour fast, the normal blood glucose level is less than 110 mg/dL, or milligrams per deciliter. A fasting blood glucose level of 126 mg/dL or higher on two separate days usually indicates diabetes.

When blood is taken randomly or without fasting first, a blood glucose level of 200 mg/dL or higher on two separate days usually indicates diabetes.

Additional blood tests can help distinguish between type 1 diabetes and other types of diabetes. The level of ketones, for example, can be measured. Ketones are usually elevated only in type 1 diabetes.

Prevention & Expectations
What can be done to prevent the disease?

Recently, scientists have begun looking into promising new ways to prevent type 1 diabetes in certain people that are at a very high risk. This is possible because scientists are now able to predict a person’s risk for developing type 1 diabetes with greater accuracy.

What are the long-term effects of the disease?
Some of the long-term effects of type 1 diabetes include:

  • Atherosclerosis, also known as hardening of the arteries, which can lead to heart attacks and strokes
  • autonomic neuropathy, which may cause digestion problems, erectile dysfunction in males, and low blood pressure
  • bacterial infections of the skin
  • Diabetic retinopathy, damage to the retina of the eye that can cause blindness
  • increased risk of dying from coronary heart disease, known as CHD
  • Diabetic nephropathy, damage to the kidneys that can lead to kidney failure
  • fungal infections like ringworm and athlete’s foot
  • peripheral neuropathy, or damage to nerves in the limbs, which can cause serious infections that may require amputation
  • urinary tract infections
  • Vaginal Yeast Infections, because high levels of blood glucose encourage the growth of yeast

Coma or death may occur as a result of diabetic ketoacidosis. In addition, smoking greatly increases the risk of getting many of these long-term effects. People with diabetes who smoke are a much higher risk for heart attacks, strokes, infections, and problems with circulation.

What are the risks to others?
Diabetes is not catching and poses no risk to others. Type 1 diabetes can sometimes run in families.

Treatment & Monitoring
What are the treatments for the disease?

Treatment for type 1 diabetes is focused on controlling blood glucose levels. This is done with insulin shots. Insulin can be injected under the skin a certain number of times per day, or may be given with an insulin pump. Home Blood glucose monitoring is also used to help guide dose adjustments. There are many types of insulin. The doctor can help decide what will work best for each person. Insulin levels must be balanced with meals, daily activities, stress, and illness, as all of these can affect the glucose level in the blood.

Treatment also includes following a proper diet for people with diabetes and getting the right amount of exercise. Less often, treatment may require a pancreas transplant, which may get rid of the symptoms of type 1 diabetes. Careful monitoring and management helps keep diabetes under control and can reduce long-term effects.

People who have type 1 diabetes can help manage it by following these steps:

  • Adjust for blood glucose levels when sick or stressed.
  • Have regular visits with a doctor.
  • Know the symptoms of hypoglycemia, which is also called low blood glucose, and how to treat it.
  • Monitor blood glucose levels at home.
  • Perform proper skin care and foot care and get regular eye examinations.
  • Plan meals and eat the right diet for a person with diabetes.
  • Take all medicines, including insulin, exactly as prescribed by the doctor.

Treating the complications of diabetes may involve several specialists. For example, eye, heart, foot, hormone, and circulation specialists may be needed. Dietitians can help people with diabetes set up an eating plan with suggestions for calorie intake and types of foods to eat.

What are the side effects of the treatments?
Too much insulin in the body means blood glucose levels can drop too low. This condition is known as hypoglycemia. It can cause nervousness, shakiness, and confusion. If this condition goes untreated, a person can pass out. The usual treatment for low blood glucose is to eat or drink something sweet. If symptoms progress to passing out, or if the person has spasms or seizures, immediate medical attention is needed.

Side effects of other treatments depend on the treatment used. A pancreas transplant is a major operation. It carries the risk of bleeding, infection, and allergic reaction to anesthesia. To prevent rejection of the new pancreas, powerful medicines with many side effects have to be taken for a long time.

What happens after treatment for the disease?
Treatment of diabetes lasts a lifetime. Type 1 diabetes cannot usually be cured, but it can be controlled with careful management and treatment. Any complications that do occur must be treated promptly.

How is the disease monitored?
Monitoring type 1 diabetes is a lifelong process. People with type 1 diabetes should check their blood glucose at least 3 times a day at home with a finger-stick blood glucose test. There are portable devices on the market that can measure blood glucose at home. Blood tests, urine tests, foot and skin exams, eye exams, and visits with specialists are all part of routine monitoring for diabetes. Any new or worsening symptoms should be reported to the doctor.

Also see:
Diabetes Health Center
Nephrogenic diabetes insipidus
Diabetes foot care
Gestational diabetes
Diabetes - Type 1
Type-2 diabetes
Type 2 Diabetes Mellitus
Diabetes and Infections

Last Edited: Aug.18, 2005

Johns Hopkins patient information

Last revised: December 5, 2012
by Potos A. Aagen, M.D.

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