When someone has diabetes, the body does not produce or use insulin properly. Insulin is a hormone needed to convert sugar, starches and other food into energy needed for life.

Diabetes is a disorder of metabolism—the way our bodies use digested food for growth and energy. Most of the food we eat is broken down into glucose, the form of sugar in the blood. Glucose is the main source of fuel for cells in the body.

After digestion, glucose passes into the bloodstream, where it is used by cells for growth and energy. For glucose to get into cells, insulin must be present. Insulin is another hormone that is produced by the pancreas, a large gland located behind the stomach.

When we eat, the pancreas automatically produces the right amount of insulin to move glucose from blood into our cells. In people with diabetes, however, the pancreas either produces too little or no insulin, or the cells do not respond appropriately to the insulin that is produced. Glucose then builds up in the blood, is filtered out in the kidneys, and passes out of the body in the urine. Thus, the body loses its main source of fuel even, though the blood contains large amounts of glucose. That is why it is crucial for diabetics to monitor blood glucose levels.

Diabetes is widely recognized as one of the leading causes of death and disability in the United States. This condition is associated with long-term complications that affect almost every part of the body. It often leads to blindness, heart and blood vessel disease, stroke, kidney failure, amputations, and diabetic nerve damage.

In 2012, diabetes cost the United States $245 billion. Indirect costs, including disability payments, time lost from work, and premature death, totaled $69 billion, and direct medical costs for diabetes care, including hospitalizations, medical care, and treatment supplies, totaled $176 billion.

3 Main Types of Diabetes

Type 1 Diabetes

Type 1 diabetes is an autoimmune disease. This condition results when the body's system for fighting infection (the immune system) turns against a part of the body. In diabetes, the immune system attacks and destroys the insulin-producing beta cells in the pancreas. The pancreas then produces little or no insulin. A person who has type 1 diabetes must take insulin daily to live.

At present, scientists do not know exactly what causes the body's immune system to attack the beta cells, but they believe that autoimmune, genetic, and environmental factors, possibly viruses, are involved. Type 1 diabetes accounts for about 5 to 10 percent of diagnosed diabetes in the United States.

Common symptoms include:

  • Increased thirst;
  • Increased urination;
  • Constant hunger;
  • Weight loss;
  • Blurred vision; and
  • Extreme fatigue.

If not diagnosed and treated with insulin, a person with type 1 diabetes can lapse into a life-threatening diabetic coma, also known as diabetic ketoacidosis.

Type 2 Diabetes

The most common form of diabetes is type 2 diabetes. About 90 to 95 percent of people with diabetes have this type. This form is most often associated with older age, obesity, family history of diabetes, and physical inactivity.

Type 2, formerly called adult-onset or non-insulin-dependent diabetes, usually begins with insulin resistance, a condition in which fat, muscle, and liver cells do not use insulin properly. At first, the pancreas keeps up with the added demand by producing more insulin. In time, however, it loses the ability to secrete enough insulin in response to meals. People who are overweight and inactive are more likely to develop type 2 diabetes.

The symptoms of type 2 diabetes develop gradually. Their onset is not as sudden as in type 1.

Symptoms may include:

  • Fatigue;
  • Frequent urination;
  • Increased thirst and hunger;
  • Weight loss;
  • Blurred vision; and
  • Slow healing of wounds or sores.

However, some people do not experience any symptoms.

(Read more on Type 2 Diabetes here.)


Pre-diabetes, also called impaired fasting glucose (IFG) or impaired glucose tolerance (IGT), means you have blood glucose levels that are higher than normal but not high enough to be called diabetes. Too much glucose in your blood can damage your body over time.

Pre-diabetes is becoming more common in the United States, according to new estimates provided by the U.S. Department of Health and Human Services. About 40 percent of U.S. adults ages 40 to 74—or 41 million people—have this condition. These people are at risk of developing full-blown type 2 diabetes within 10 years.

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The good news is that if you have pre-diabetes, you can do a lot to prevent or delay the worsening of your condition. Studies have clearly shown that you can lower your risk by losing 5 to 7 percent of your body weight through diet and increased physical activity. A major study of more than 3,000 people with IGT, a form of pre-diabetes, found that diet and exercise resulting in this amount of weight loss lowered the incidence of type 2 diabetes by nearly 60 percent. Study participants lost weight by cutting fat and calories in their diet and by exercising (most chose walking) at least 30 minutes a day, 5 days a week.

Adults with diabetes are at high risk for cardiovascular disease (CVD). In fact, at least 65 percent of those with diabetes die from heart disease or stroke. Managing diabetes is more than keeping blood glucose levels under control—it is also important to manage blood pressure and cholesterol levels through healthy eating, physical activity, and use of medications (if needed). By doing so, those with diabetes can lower their risk. Aspirin therapy, if recommended by the health care team, and smoking cessation can also help lower risk.

Managing Diabetes

People with diabetes must take responsibility for their day-to-day care. Much of the daily care involves testing blood glucose levels to keep them from going too low or too high. When blood glucose levels drop too low—a condition known as hypoglycemia—a person can become nervous, shaky, and confused. Judgment can be impaired, and if blood glucose falls too low, fainting can occur. A person can also become ill if blood glucose levels rise too high, a condition known as hyperglycemia.

Healthy eating, physical activity, and blood glucose testing are the basic management tools for type 2. In addition, many people require oral medication, insulin, or both to control their glucose levels. Controlling blood pressure and cholesterol is also important and a daily aspirin regimen may be needed.

People with diabetes should see a health care provider who will help them learn to manage their condition. Most people with diabetes get care from primary care physicians like internists, family practice doctors, or pediatricians. Often, having a team of providers can improve diabetes care. A team can include these PCPs, an endocrinologist (a specialist in diabetes care), a dietitian, a nurse, a podiatrist (for foot care), an ophthalmologist or an optometrist (for eye care).

The ultimate goal of management is to keep levels of blood glucose, blood pressure, and cholesterol as close to the normal range as safely possible.