College of American Pathologists
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  Diabetes Testing Information




Updated December 2, 2008

What is diabetes?

Diabetes affects nearly 23.6 million people and is the seventh leading cause of death in the United States. A diagnosis of diabetes means that your body is either not producing or not using insulin as effectively as it should. Insulin, a hormone secreted by the pancreas, is used to convert sugar (glucose) into the energy your body needs. When you have diabetes, sugars build up in your blood stream. If left untreated, these elevated sugars can damage your heart, blood vessels, kidneys, nerves, and eyes.

There are two primary forms of diabetes—type 1 and type 2. Five to 10 percent of people with diabetes have type 1, a form of the disease predominately found in children and young adults. Type 2, the most common form of diabetes, is usually diagnosed in adults, primarily in those over the age of 55. However, because 80 percent of people with type 2 diabetes are overweight, as the rate of obesity has risen in children, so has the number of children and young adults who are diagnosed with type 2 diabetes.

Before people develop type 2 diabetes, they almost always have “pre-diabetes”—blood glucose levels that are higher than normal but not yet high enough to be diagnosed as diabetes. Today, 57 million people in the United States have pre-diabetes. Research has also shown that if you take action to manage your blood glucose when you have pre-diabetes, you can delay or prevent type 2 diabetes from ever developing.

What are the different types of diabetes?

There are three main types of diabetes: type 1, type 2, and gestational diabetes.  

Type 1 diabetes is an autoimmune disease and is most often diagnosed in children. For an unexplained reason, the body’s immune system destroys the insulin-producing cells in the pancreas. Because the pancreas produces little or no insulin, a person with type 1 diabetes needs to take insulin daily to survive. Type 1 diabetes accounts for 5 to 10 percent of all diabetes cases in the United States.

Type 2 diabetes is the most common form of diabetes. It is usually diagnosed in adults, usually in those over the age of 55. People with type 2 diabetes may initially produce enough insulin, but the body is unable to use the insulin effectively. After several years the insulin production stops or slows down and glucose levels rise.

Gestational diabetes only occurs in pregnant women. It has many of the same risk factors as type 2 diabetes, but often disappears after the birth. Women who develop gestational diabetes are at a greater risk for developing type 2 diabetes during their lives.

Why have a diabetes test?

Diabetes affects 23.6 million people of all ages in the U.S.—an increase of 13.5 percent from 2005 to 2007. About eight percent of the American population has diabetes, yet about one-forth of individuals with the disease are unaware they have it. The disease can develop slowly and complications may already be present by the time the diagnosis is made.

Most people first become aware of their diabetes through a routine blood test or a blood test done for another condition.

There are two types of tests to diagnose diabetes—a fasting plasma glucose test in which blood sugar levels are measured after fasting for eight hours, or an oral glucose tolerance test, in which blood sugar levels are tested after drinking a sweet liquid that contains glucose, a type of sugar. Because blood sugar is affected dramatically by diet, the fasting test is the preferred method for diagnosis.

Who should be screened for diabetes?

All adults should have a fasting glucose test at age 45. If diabetes is not detected, the test probably does not have to be repeated for three years. However, you should discuss with your physician the best screening schedule based on your risk factors. For example, your physician may wish to test you more frequently if you are overweight or have a family history of diabetes.  

Are some ethnic groups at a higher risk for diabetes than others?

While African Americans, Hispanics and Native Americans have a greater risk of developing type 2 diabetes than do Caucasians, Caucasians are more at risk for type 1. Both African Americans and Hispanic Americans are two times more likely to develop diabetes than whites. Native Americans are nearly three times more likely to have diabetes.

Does my age put me at a higher risk for diabetes?

Yes, the risk of type 2 diabetes increases as you become older. In fact, nearly 20 percent of people 65 years or older have the disease. However, as obesity rates in young populations increase, physicians are seeing more young people, including children, with type 2 diabetes.

What different tests are used to screen and monitor diabetes?

Several different tests detect diabetes including a random sugar test (normally part of a routine blood test) and a fasting plasma glucose test. Because blood sugar is affected dramatically by diet, the fasting test is the preferred method for diagnosis. For this test, you must fast (no food, but water is allowed) for at least eight hours. Another test that can be used to diagnose diabetes is the oral glucose tolerance test (OGTT), but this is less reliable than a fasting glucose test. An OGTT test measures your glucose after consuming a sugar-water drink during a three-hour interval.

For all the tests, blood will be drawn and sent to the laboratory for analysis. A pathologist will report your glucose levels back to your physician and he or she will evaluate your results and symptoms. A fasting glucose level above 125 mg/dl or an OGTT level above 199 mg/dl usually indicates diabetes. A confirmed diagnosis is made after two positive tests, with the second test taken on a different day.

Once you are diagnosed with diabetes, it may be necessary for you to monitor your sugar levels with a finger-prick test at different times of the day. For this test, you need to put a small amount of blood on a test strip that is read by a blood glucose meter. All the supplies needed can usually be found at your local pharmacy.

What are the symptoms of diabetes?

Most people with type 2 diabetes do not recognize the symptoms because the disease develops slowly. When you have too much blood sugar or glucose in your body, it can draw water from the body’s tissues. Hence, many of the symptoms of diabetes are a direct result of your body’s reaction to this dehydration.

Symptoms include:

  • Excessive thirst
  • Unexplained weight loss or gain. As your body tries to compensate for the loss of fluids and sugar, you may have the urge to eat more and gain weight. Alternatively, because your muscles are not receiving the glucose they need, you may lose weight as your body burns stored calories to create energy.
  • Blurred vision
  • Tingling or numbness in the hands and feet caused by nerve damage
  • Very dry skin
  • Flu-like symptoms, including excessive fatigue

How is diabetes treated?

The key to successful diabetes treatment is effectively monitoring and managing your blood sugar levels. This can often be achieved through diet that focuses particularly on weight loss and exercise. If this doesn’t work for you, your physician may prescribe insulin or other medications to lower your blood sugar.

Whether you require medication or not, consistent monitoring of your blood sugar levels is a vital component of diabetes treatment. Regular monitoring at the time intervals recommended by your doctor allows you and your doctor to see if a prescribed treatment is working, or if your glucose levels remain high.

How are diabetes and obesity related, especially in children?

Being overweight is the number one risk factor for developing type 2 diabetes. When your body carries excess fatty tissue, especially in the abdomen, your cells start to resist your own insulin, and blood sugar levels eventually rise. According to national statistics, nearly 15 percent of children are now categorized as seriously overweight. As a result, in the past two decades, type 2 diabetes has more than quadrupled among children.

A child’s risk for diabetes can be controlled with the proper diet and increased activity. Parents can reduce “couch potato” time in front of the television, computer, and video games and plan activities for their children where they are active and not as likely to snack, like a family hike or bike trip.

How can I prevent diabetes?

Although some risk factors such as race, age, and family history cannot be controlled, you can control the main risk factor for type 2 diabetes—excess weight. When your body has excess fatty tissue, the cells become more resistant to your own insulin. Research shows that even a small weight loss, such as 10 to 20 pounds, can protect you from developing diabetes.

Besides maintaining an appropriate weight, exercise is important to prevent diabetes. As little as 30 minutes of moderate exercise, such as walking, most days of the week can decrease your risk of diabetes. In addition to helping you control your weight, blood pressure and cholesterol levels, physical activity helps increase your muscle mass. Muscle uses a large percentage of your body’s glucose, which leaves less in the blood stream.

My doctor says I have pre-diabetes. What is that?

Pre-diabetes is when your blood glucose levels are elevated, but not high enough to be considered diabetes. Often by taking action when you are diagnosed with pre-diabetes, you can prevent development of type 2 diabetes. Diet and exercise are the best treatment for pre-diabetes. Thirty minutes of moderate physical activity daily and a small reduction in body weight can reduce your chance of developing diabetes by more than 50 percent.

Are people with diabetes at risk for other illnesses?

People with diabetes are at risk for both long- and short-term compilations. In the short-term they may suffer from hypoglycemia (low blood sugar) or, alternatively, high blood sugar. Both can be deadly and most often occur in a person with diabetes who fails to monitor his or her blood sugar regularly.

Long-term complications from diabetes are more common. People with diabetes are at risk for nerve damage, caused when excessive sugar effects the walls of the blood vessels that nourish your nerves. This most often causes a tingling in your toes or fingers and if not treated can cause you to lose all sense of feeling in a limb. In addition, people with diabetes often suffer damage to the heart, eyes and kidneys and their ability to fight off infections.

Does diabetes put me at greater risk for heart disease?

Heart disease is the leading cause of death for people with diabetes. In fact, adults with diabetes have a two-to-four times greater chance of dying from heart disease than individuals without diabetes. People with diabetes often have higher rates of high blood pressure, high cholesterol, and obesity, all risk factors for heart disease.  

How does diabetes put me at greater risk for amputation?

More than 60 percent of all non-traumatic lower-limb amputations occur in people with diabetes. Diabetes can cause nerve damage and reduced blood flow to the feet. As a result, you may not notice a sore before it becomes infected, allowing the infection to spread and become untreatable except with amputation.

Does diabetes affect my vision?

Diabetes is the leading cause of new cases of blindness among adults. Because diabetes leads to damage to all the body’s blood vessels, including the small vessels that supply blood to the eye, the eye is deprived the regular flow of blood it needs to function properly. This can lead to damage of the retina, the part of the eye that sends signals to the brain. If this damage is detected early, it can often be treated, so it is important for people with diabetes to have regular eye check-ups.

Are my kidneys at risk when I have diabetes?

Your kidneys contain many tiny blood vessels that work to filter waste from your body. Unfortunately, elevated sugar levels can cause too much blood to be filtered through the kidney, making it work extra hard. This stress causes the kidneys to lose their ability to filter waste and can lead to renal-failure. If not detected early enough, a kidney transplant or dialysis may be needed.

How can diabetes affect my ability to fight infections?

An elevated blood sugar prevents your body’s white blood cells from fighting infection. As a result, coupled with the fact you may not notice a cut or ulcer because of a loss of feeling to the feet, people with diabetes have a higher rate of infection than the general population. To prevent infections and their serious complications, people with diabetes should examine their feet daily for cuts or scrapes and see their physician immediately if they have a minor injury that is not healing.

If I am pregnant, does diabetes affect my health and my baby's health?

Women with diabetes who plan to become pregnant should work to bring their blood sugar levels under control to avoid risks to themselves and the fetus. Poorly controlled diabetes can lead to serious birth defects to the heart, brain, or spinal column. Pregnant women with diabetes who don’t control their sugar levels are also at a greater risk for stillbirth and miscarriage. In addition, the mother is at an increased risk for pregnancy-related high blood pressure.

Women who develop gestational diabetes usually do not have an increased risk for a baby born with birth detects. However, because babies of these mothers are often larger, the babies are at risk for injuries during delivery.

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