What is diabetes?
Diabetes means your blood glucose (often called blood sugar) is too high. Too much glucose in the blood isn't good for your health.
Diabetes is a disorder of metabolism—the way the body uses digested food for growth and energy. Most of the food people eat is broken down into glucose, the form of sugar in the blood. Glucose is the main source of fuel for 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 a hormone produced by the pancreas, a large gland behind the stomach.
When people eat, the pancreas automatically produces the right amount of insulin to move glucose from blood into the cells. In people with diabetes, however, the pancreas either produces little or no insulin, or the cells do not respond appropriately to the insulin that is produced. Glucose builds up in the blood, overflows into the urine, 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.
Diabetes is a serious, life-long disease. It cannot be cured, but control of blood glucose, blood pressure, and cholesterol can prevent or delay the complications of this disease.
What are the types of diabetes?
The three main types of diabetes are:
- type 1 diabetes
- type 2 diabetes
- gestational diabetes
What is Type 1 Diabetes?
Type 1 diabetes is an autoimmune disease. An autoimmune disease 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. It develops most often in children and young adults but can appear at any age.
Symptoms of type 1 diabetes usually develop over a short period, although beta cell destruction can begin years earlier. Symptoms may include increased thirst and 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.
What is Type 2 Diabetes?
The most common form of diabetes is type 2 diabetes. About 90 to 95 percent of people with diabetes have type 2. This form of diabetes is most often associated with older age, obesity, family history of diabetes, previous history of gestational diabetes, physical inactivity, and certain ethnicities. About 80 percent of people with type 2 diabetes are overweight.
Type 2 diabetes is increasingly being diagnosed in children and adolescents, especially among African American, Mexican American, and Pacific Islander youth.
When type 2 diabetes is diagnosed, the pancreas is usually producing enough insulin, but for unknown reasons the body cannot use the insulin effectively, a condition called insulin resistance. After several years, insulin production decreases. The result is the same as for type 1 diabetes—glucose builds up in the blood and the body cannot make efficient use of its main source of fuel.
The symptoms of type 2 diabetes develop gradually. Their onset is not as sudden as in type 1 diabetes. Symptoms may include fatigue, frequent urination, increased thirst and hunger, weight loss, blurred vision, and slow healing of wounds or sores. Some people have no symptoms.
What is Gestational Diabetes?
Gestational diabetes is a type if diabetes that can develop in women who are pregnant. Some women develop gestational diabetes late in pregnancy. Although this form of diabetes usually disappears after the birth of the baby, women who have had gestational diabetes have a 40 to 60 percent chance of developing type 2 diabetes within 5 to 10 years. Maintaining a reasonable body weight and being physically active may help prevent development of type 2 diabetes.
About 3 to 8 percent of pregnant women in the United States develop gestational diabetes. As with type 2 diabetes, gestational diabetes occurs more often in some ethnic groups and among women with a family history of diabetes. Gestational diabetes is caused by the hormones of pregnancy or a shortage of insulin. Women with gestational diabetes may not experience any symptoms.
What are the signs of diabetes?
- being very thirsty
- urinating a lot
- feeling very hungry
- feeling very tired
- losing weight without trying
- having sores that are slow to heal
- having dry, itchy skin
- losing feeling in or having tingling in the hands or feet
- having blurry vision
- having more infections than usual If you have one or more of these signs, see your doctor.
How is diabetes diagnosed?
The fasting blood glucose test is the preferred test for diagnosing diabetes in children and nonpregnant adults. The test is most reliable when done in the morning. However, a diagnosis of diabetes can be made based on any of the following test results, confirmed by retesting on a different day:
A blood glucose level of 126 milli grams per deciliter (mg/dL) or higher after an 8-hour fast. This test is called the fasting blood glucose test.
A blood glucose level of 200 mg/dL or higher 2 hours after drinking a beverage containing 75 grams of glucose dissolved in water. This test is called the oral glucose tolerance test (OGTT).
A random—taken at any time of day—blood glucose level of 200 mg/dL or higher, along with the presence of diabetes symptoms.
Gestational diabetes is diagnosed based on blood glucose levels measured during the OGTT. Glucose levels are normally lower during pregnancy, so the cutoff levels for diagnosis of diabetes in pregnancy are lower. Blood glucose levels are measured before a woman drinks a beverage containing glucose. Then levels are checked 1, 2, and 3 hours afterward. If a woman has two blood glucose levels meeting or exceeding any of the following numbers, she has gestational diabetes: a fasting blood glucose level of 95 mg/dL, a 1-hour level of 180 mg/dL, a 2-hour level of 155 mg/dL, or a 3-hour level of 140 mg/dL.
Why does being overweight or obese put me at risk for developing diabetes?
Your weight affects your health in many ways. Being overweight can keep your body from making and using insulin properly. It can also cause high blood pressure. Overweight people are twice as likely to develop type 2 diabetes as people who are not overweight. You can reduce your risk of developing this type of diabetes by losing weight and by increasing your physical activity.
How is diabetes managed?
Before the discovery of insulin in 1921, everyone with type 1 diabetes died within a few years after diagnosis. Although insulin is not considered a cure, its discovery was the first major breakthrough in diabetes treatment.
Today, healthy eating, physical activity, and taking insulin are the basic therapies for type 1 diabetes. The amount of insulin must be balanced with food intake and daily activities. Doctors may also prescribe another type of injectable medicine. Blood glucose levels must be closely monitored through frequent blood glucose checking. People with diabetes also monitor blood glucose levels several times a year with a laboratory test called the A1C. Results of the A1C test reflect average blood glucose over a 2- to 3-month period.
Healthy eating, physical activity, and blood glucose testing are the basic management tools for type 2 diabetes. In addition, many people with type 2 diabetes require one or more diabetes medicines—pills, insulin, and other injectable medicine—to control their blood glucose levels.
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 the use of medications, if needed. By doing so, those with diabetes can lower their risk. Aspirin therapy, if recommended by a person’s health care team, and smoking cessation can also help lower risk.
People with diabetes must take responsibility for their day-to-day care. Much of the daily care involves keeping blood glucose levels 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.
People with diabetes should see a health care provider who will help them learn to manage their diabetes and who will monitor their diabetes control. Most people with diabetes get care from primary care physicians—internists, family practice doctors, or pediatricians. Often, having a team of providers can improve diabetes care. A team can include:
- a primary care provider such as an internist, a family practice doctor, or a pediatrician
- an endocrinologist—a specialist in diabetes care
- a dietitian, a nurse, and other health care providers who are certified diabetes educators—experts in providing information about managing diabetes
- a podiatrist—for foot care
- an ophthalmologist or an optometrist—for eye care
The team can also include other health care providers, such as cardiologists and other specialists. The team for a pregnant woman with type 1, type 2, or gestational diabetes should include an obstetrician who specializes in caring for women with diabetes. The team can also include a pediatrician or a neonatologist with experience taking care of babies born to women with diabetes.
The goal of diabetes management is to keep levels of blood glucose, blood pressure, and cholesterol as close to the normal range as safely possible. A major study, the Diabetes Control and Complications Trial (DCCT), sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), showed that keeping blood glucose levels close to normal reduces the risk of developing major complications of type 1 diabetes.
This 10-year study, completed in 1993, included 1,441 people with type 1 diabetes. The study compared the effect of two treatment approaches—intensive management and standard management—on the development and progression of eye, kidney, nerve, and cardiovascular complications of diabetes. Intensive treatment aimed to keep A1C levels as close to normal—6 percent—as possible. Researchers found that study participants who maintained lower levels of blood glucose through intensive management had significantly lower rates of these complications. More recently, a follow-up study of DCCT participants showed that the ability of intensive control to lower the complications of diabetes has persisted more than 10 years after the trial ended.
The United Kingdom Prospective Diabetes Study, a European study completed in 1998, showed that intensive control of blood glucose and blood pressure reduced the risk of blindness, kidney disease, stroke, and heart attack in people with type 2 diabetes.
What kinds of medication do people take for diabetes?
Controlling blood glucose is the best defense against the serious complications of diabetes. Insulin and diabetes pills are the two kinds of medicines used to lower blood glucose.
You need insulin if your body has stopped making insulin or if it doesn't make enough. Everyone with type 1 diabetes needs insulin, and many people with type 2 diabetes do, too. If your body makes insulin but the insulin doesn't lower your blood glucose, you may need diabetes pills.
What are some of the complications of diabetes?
A key goal of diabetes treatment is to prevent complications because, over time, diabetes can damage the heart, blood vessels, eyes, kidneys, and nerves, although the person may not know damage is taking place. It's important to diagnose and treat diabetes early, because it can cause damage even before it makes someone feel ill.
How diabetes causes long-term problems is unclear. However, changes in the small blood vessels and nerves are common. These changes may be the first step toward many problems that diabetes causes. Scientists can't predict who among people with diabetes will develop complications, but complications are most likely to occur in someone who has had diabetes for many years. However, because a person can have diabetes without knowing it, a complication may be the first sign.
Heart disease is the most common life-threatening disease linked to diabetes, and experts say diabetes doubles a person's risk of developing heart disease. In heart disease, deposits of fat and cholesterol build-up in the arteries that supply the heart with blood. If this buildup blocks blood from getting to the heart, a potentially fatal heart attack can occur.
Other risk factors include hypertension or high blood pressure, obesity, high amounts of fats and cholesterol in blood, and cigarette smoking. Eliminating these risk factors, along with treating diabetes, can reduce the risk of heart disease. The American Heart Association has literature that explains what heart disease is and how to prevent it. The association's address is in the resources section of this hypertext.
People with diabetes are also more likely to develop kidney disease than other people. The kidneys filter waste products from the blood and excrete them in the form of urine, maintaining proper fluid balance in the body. While people can live without one kidney, those without both must have special treatment, called dialysis. Most people with diabetes will never develop kidney disease, but proper diabetes treatment can further reduce the risk. High blood pressure also can add to the risk of kidney disease. Therefore, regular blood pressure checks and early treatment of the disorder can help prevent kidney disease.
Urinary tract infections are also a cause of kidney problems. Diabetes can affect the nerves that control the bladder, making it difficult for a person to empty his or her bladder completely. Bacteria can form in the unemptied bladder and the tubes leading from it, eventually causing infection. The symptoms of a urinary tract infection include frequent, painful urination, blood in the urine, and pain in the lower abdomen and back. Without prompt examination and treatment by a doctor, the infection can reach the kidneys, causing pain, fever, and possibly kidney damage. A doctor may prescribe antibiotics to treat the infection and may suggest that the person drink large amounts of water.
Kidney problems are one cause of water retention, or edema, a condition in which fluid collects in the body, causing swelling, often in the legs and hands. A doctor can decide if swelling or water retention relates to kidney function.
A nephrologist, a doctor specially trained to diagnose and treat kidney problems, can identify the cause of problems and recommend ways to reduce the risk of kidney disease.
Diabetes can affect the eyes in several ways. Frequently, the effects are temporary and can be corrected with better diabetes control. However, long-term diabetes can cause changes in the eyes that threaten vision. Stable blood glucose levels and yearly eye examinations can help reduce the risk of serious eye damage.
Blurred vision is one effect diabetes can have on the eyes. The reason may be that changing levels of glucose in blood also can affect the balance of fluid in the lens of the eye, which works like a flexible camera lens to focus images. If the lens absorbs more water than normal and swells, its focusing power changes. Diabetes also may affect the function of nerves that control eyesight, causing blurred vision.
Cataract and glaucoma are eye diseases that occur more frequently in people with diabetes. Cataract is a clouding of the normally clear lens of the eye. Glaucoma is a condition in which pressure within the eye can damage the optic nerve that transmits visual images to the brain. Early diagnosis and treatment of cataract and glaucoma can reduce the severity of these disorders.
Retinopathy, a disease of the retina, the light sensing tissue at the back of the eye, is a common concern among people with diabetes. Diabetic retinopathy damages the tiny vessels that supply the retina with blood. The blood vessels may swell and leak fluid. When retinopathy is more severe, new blood vessels may grow from the back of the eye and bleed into the clear gel that fills the eye, the vitreous.
While most people with diabetes may never develop serious eye problems, people who have had diabetes for 25 years are more likely to develop retinopathy. Experts think high blood pressure may contribute to diabetic retinopathy, and that smoking can cause the condition to worsen. If someone experiences blurred vision that lasts longer than a day or so, sudden loss of vision in either eye, or black spots, lines, or flashing lights in the field of vision, a doctor should be alerted right away.
Treatment for diabetic retinopathy can help prevent loss of vision and can sometimes restore vision lost because of the disease. A yearly eye examination with dilated pupils makes it possible for an ophthalmologist, an eye doctor, to notice changes before the illness becomes harder to treat. Scientists are testing new means of treating diabetic retinopathy. For more information on eye complications of diabetes and the treatment of these conditions, see the resource list at the end of this hypertext document.
Legs and Feet
Leg and foot problems can arise in people with diabetes due to changes in blood vessels and nerves in these areas. Peripheral vascular disease is a condition in which blood vessels become narrowed by fatty deposits, reducing blood supply to the legs and feet. Diabetes also can dull the sensitivity of nerves. Someone with this condition, called peripheral neuropathy, might not notice a sore spot caused by tight shoes or pressure from walking. If ignored, the sore can become infected, and because blood circulation is poor, the area may take longer to heal.
Proper foot care and regular visits to a doctor can prevent foot and leg sores and ensure that any that do appear don't become infected and painful. Helpful measures include inspecting the feet daily for cuts or sore spots. Blisters and sore spots are not as likely when shoes fit well and socks or stockings aren't tight. A doctor also may suggest washing feet daily, with warm, not hot water; filing thick calluses; and using lotions that keep the feet from getting too dry. Shoe inserts or special shoes can be used to prevent pressure on the foot.
Diabetic neuropathy, or nerve disease, dulls the nerves and can be extremely painful. A person with neuropathy also may be depressed. Scientists aren't sure whether the depression is an effect of neuropathy, or if it's simply a response to pain. Treatment, aimed at relieving pain and depression, may include aspirin and other pain-killing drugs.
Any sore on the foot or leg, whether or not it's painful, requires a doctor's immediate attention. Treatment can help sores heal and prevent new ones from developing. Problems with the feet and legs can cause life-threatening problems that require amputation-surgical removal of limbs if not treated early.
Other Effects of Diabetic Neuropathy
Nerves provide muscle tone and feeling and help control functions like digestion and blood pressure. Diabetes can cause changes in these nerves and the functions they control. These changes are most frequent in people who have had other complications of diabetes, like problems with their feet. Someone who has had diabetes for some years and has other complications, may find that spells of indigestion or diarrhea are common. A doctor may prescribe drugs to relieve these symptoms. Diabetes also can affect the nerves that control penile erection in men, which can cause impotence that shows up gradually, without any loss of desire for sex. A doctor can find out whether impotence is the result of physical changes, such as diabetes, or emotional changes, and suggest treatment or counseling.
Skin and Oral Infections
People with diabetes are more likely to develop infections, like boils and ulcers, than the average person. Women with diabetes may develop vaginal infections more often than other women. Checking for infections, treating them early, and following a doctor's advice can help ensure that infections are mild and infrequent. Infections also can affect the teeth and gums, making people with diabetes more susceptible to periodontal disease, an inflammation of tissue surrounding and supporting the teeth. An important cause of periodontal disease is bacterial growth on the teeth and gums. Treating diabetes and following a dentist's advice on dental care can help prevent periodontal disease.
Very high blood glucose levels cause symptoms that are hard to ignore: frequent urination and excessive thirst. However, in someone who is elderly or in poor health these symptoms may go unnoticed. Without treatment, a person with high blood glucose or hyperglycemia can lose fluids, become weak, confused, and even unconscious. Breathing will be shallow and the pulse rapid. The person's lips and tongue will be dry, and his or her hands and feet will be cool. A doctor should be called immediately.
The opposite of high blood glucose, very low blood glucose or hypoglycemia, is also dangerous. Hypoglycemia can occur when someone hasn't eaten enough to balance the effects of insulin or oral medicine. Prolonged, strenuous exercise in someone taking oral diabetes drugs or insulin also can cause hypoglycemia, as can alcohol.
Someone whose blood glucose has become too low may feel nervous, shaky, and weak. The person may sweat, feel hungry, and have a headache. Severe hypoglycemia can cause loss of consciousness. A person with hypoglycemia who begins to feel weak and shaky should eat or drink something with sugar in it immediately, like orange juice. If the person is unconscious, he or she should be taken to a hospital emergency room right away. An identification bracelet or necklace that states that the wearer has diabetes will let friends know that these symptoms are a warning of illness that requires urgent medical help.