Diabetes mellitus, often simply called diabetes, is a common disorder in which the body cannot properly use the carbohydrates (starches and simple sugars), fats and proteins in foods. All of these nutrients can be processed by the liver into one type of simple sugar, glucose, which then enters the bloodstream. All body cells require glucose for energy. Glucose enters body cells with the help of a hormone called insulin, which acts somewhat like a gatekeeper. If the body becomes less responsive to insulin, or if the body is not producing insulin, glucose cannot pass through the cell wall and the cell "starves." Because the glucose cannot enter cells, it remains in the blood, which is why people with diabetes have high blood sugar. As a result of cellular starvation and high blood sugar, the body has to work harder to keep functioning, and organs and systems can suffer severe damage.

There are three types of diabetes mellitus:

Type 1 diabetes, sometimes called insulin-dependent diabetes mellitus or juvenile-onset diabetes — Only about 5 percent to 10 percent of people with diabetes have type 1. It typically is diagnosed before age 35, most often during adolescence. In type 1, some or all of the insulin-producing cells of the pancreas (called beta cells) are destroyed by the body's own immune system, leaving the patient with little or no naturally produced insulin.

What causes the immune system to attack the beta cells is a mystery. Both genetics and environment play a part, with the disease being triggered in genetically susceptible people by some outside factor. Viral infections and drinking cow's milk early in life are two possible triggers.

Type 2 diabetes, previously called non-insulin-dependent diabetes mellitus or adult-onset diabetes — About 90 percent to 95 percent of people with diabetes have type 2. Although type 2 diabetes is diagnosed mostly in people older than age 40, it is becoming increasingly common in young adults and children. In type 2, the pancreas produces amounts of insulin that would ordinarily be sufficient, but the body cells become resistant to insulin, meaning the cells do not respond to insulin unless it is produced in much larger amounts. Insulin, then, loses its gatekeeper abilities, and glucose is not able to enter the cells. Initially, the pancreas increases its output of insulin to try to make up for the cells' insulin resistance, but eventually, insulin production falls as the pancreas tires of producing extra insulin. At this point, blood sugar levels will rise and the person will begin to experience symptoms of diabetes.

Type 2 diabetes has a genetic component and is associated with obesity, although not everyone with type 2 diabetes is overweight. Fat accumulation around the waist can lead to a more serious condition known as metabolic syndrome, insulin-resistance syndrome, or syndrome X. Metabolic syndrome includes a cluster of conditions: insulin resistance, increased blood levels of insulin (hyperinsulinemia), high blood pressure, elevated levels of triglycerides, low levels of protective high-density lipoprotein cholesterol, and an increased incidence of atherosclerosis (narrowing of the arteries).

Gestational diabetes, also known as diabetes of pregnancy — This form of diabetes usually disappears after the baby is born.

The initial symptoms of diabetes are related to high blood glucose levels. These symptoms include excessive urination, thirst and hunger, weight loss, and increased susceptibility to infections, especially of the skin and vagina. Extremely high blood sugar levels can lead to a dangerous complication called hyperglycemic hyperosmolar coma. Usually seen in people with type 2 diabetes, hyperglycemic hyperosmolar coma is a state of mental confusion and disorientation that can progress to loss of consciousness and is associated with extreme dehydration. It can be the first sign of undiagnosed type 2 diabetes.

People with diabetes who have had high blood sugar levels for long periods of time can develop complications, including:

• Damage to the eyes (retinopathy) which can lead to blindness
• Damage to the nerves (neuropathy), which can lead to numbness, tingling or pain in the legs and arms
• Damage to the kidneys (nephropathy), which can result in kidney failure

People with diabetes also are at increased risk of cardiovascular disease caused by atherosclerosis (thickening and hardening of the artery). Atherosclerosis can involve the:

• Heart (coronary heart disease), with symptoms of chest pain or heart attack
• Brain (cerebrovascular disease), causing stroke
• Arteries supplying the legs (peripheral vascular disease), causing leg pain while walking or exercising that stops quickly with rest

People with diabetes who have peripheral nerve damage and poor circulation associated with peripheral vascular disease eventually can develop foot ulcers and infections, which can lead to gangrene (dead tissue and skin) and amputation.

The main test used to diagnose diabetes is a blood test that measures the amount of glucose in your blood. The test is performed in the morning, after you have fasted overnight. The diagnosis of diabetes is made when fasting blood glucose is greater than 126 milligrams per deciliter on more than one blood test.

Another blood test that may be done is called hemoglobin A1C, which measures average blood glucose over the preceding two months. Although this test is not used to diagnose diabetes, it is helpful for your doctor to measure it when you are first diagnosed. The success of treatment then can be measured by comparing later A1C numbers to your baseline.

When diabetes has been diagnosed, your doctor will use your age, body weight, family history, and other medical history to decide what type of diabetes (type 1 or type 2) is most likely. Your doctor also will check for signs of developing complications and other health problems that commonly occur with diabetes. For example, your doctor will check for high blood pressure; signs of retinopathy; decreased sensation and reflexes in the legs; poor pulses in the feet; blisters, ulcers or infections of the feet; and abnormal heart rhythm. Your doctor also may want to measure the level of creatinine in the blood and/or check for small amounts of protein in the urine (called a microalbumin test). Both of these tests are used to check for evidence of kidney disease. A blood test called a lipid profile (cholesterol, triglycerides, high-density lipoprotein, and low-density lipoprotein cholesterol) may be done to evaluate the risk of atherosclerosis.

Diabetes is a lifelong illness. Some people with type 2 diabetes are able to reduce their blood sugars to normal levels through diet and exercise, but even these people should continue to identify themselves as diabetic and be monitored closely by a physician. In such cases, aging or episodic illness typically causes the body's insulin resistance to increase, so additional treatment may be required over time.

There is currently no effective prevention for type 1 diabetes. However, it's possible to prevent the most common type of diabetes, type 2. Because prevention strategies are available, it is worthwhile to have your blood sugar tested if you have risk factors for diabetes, such as obesity or a family history of diabetes. Mild elevations in blood sugar signify a condition called impaired glucose tolerance or impaired fasting glucose. These blood sugar elevations show that your body is developing insulin resistance, which typically leads to diabetes. Without changes in lifestyle or medication, you have about a 10 percent chance per year of progressing to diabetes if you have elevated blood sugar. A large three-year study that ended in 2002 showed that people with elevated blood sugar could cut their risk of progressing to diabetes by more than half, if they ate a reduced calorie diet, exercised regularly, and lost a modest amount of weight. A medication called metformin (Glucophage) also offered some protection.

If you already have diabetes, you can delay or prevent late complications (retinopathy, neuropathy, nephropathy) by controlling your blood sugar. You can lower your risk of cardiovascular complications by minimizing any other risk factors for atherosclerosis, such as high blood pressure, high blood levels of cholesterol and triglycerides, cigarette smoking, and obesity.

Currently, treatment of type 1 diabetes requires insulin to be injected under the skin to make up for the insulin not produced by the body. Patients can use syringes, injector pens, or an insulin pump. In order to properly regulate insulin intake, people with type 1 diabetes need to monitor their blood sugar levels several times per day by testing a small sample of blood.

People with type 1 diabetes also need to watch their diets and get regular exercise. A healthy diet for type 1 diabetics is one that keeps the amount of glucose entering the blood relatively constant, which makes it easier to control with insulin. Exercise helps keep blood vessels healthy, promotes glucose usage by muscles, and keeps body weight down.

For people with type 2 diabetes, treatment begins with weight reduction through diet and exercise. The recommended diet is a reduced-calorie diet that is usually the same as the diet traditionally used to lower cholesterol and prevent cardiovascular disease. Initially, most patients with type 2 diabetes can control their blood sugar with medications taken by mouth. Insulin often is used in small doses before bed to help prevent release of glucose from the liver during sleep. In advanced type 2 diabetes, insulin may be needed more than once per day in higher doses.

If you take more insulin or diabetes medication than is needed to balance the diet's daily calories, blood sugar levels can drop and cause hypoglycemia (low blood sugar). Symptoms of hypoglycemia include sweating, trembling, dizziness, hunger, confusion, seizures and loss of consciousness.

Because people with diabetes are at an increased risk of dehydration, if you have diabetes, you should call your doctor whenever you have nausea and vomiting, especially if your fluid intake is poor.

If you have diabetes, see your doctor regularly (as your doctor advises) to make sure that you are keeping good control of your blood sugar and to be checked for early signs of complications, such as heart disease, eye problems, and skin infections. Your doctor most likely will suggest that you periodically visit other specialists, such as a podiatrist to check your feet and an ophthalmologist to check for signs of diabetes complications that affect the eye.

Call your doctor immediately if your blood glucose is extremely high (greater than 500, for example), especially if you also have any of the following problems: an acute illness, extreme thirst with an inability to drink fluids because of nausea, vomiting, confusion or loss of consciousness.

Because of the dangerous complications that diabetes can cause, this disease is a very serious health risk. As a group, diabetics have twice the risk of dying at a premature age and have two to four times the average risk of heart attack and stroke. However, there is a great deal you can do to reduce your personal risk of diabetes complications. A "healthy diabetic," who is able to carefully control blood glucose and who makes every effort to reduce risk factors for cardiovascular disease, has a dramatically reduced risk of diabetes complications.

American Diabetes Association
ATTN: Customer Service
1701 N. Beauregard St.
Alexandria, VA 22311
Toll-Free: (800) 342-2383
E-Mail: customerservice@diabetes.org
http://www.diabetes.org/

National Institute on Deafness and Other Communication Disorders
NIDCD Information Clearinghouse
1 Communication Avenue.
Bethesda, MD 20892
Phone: (301) 496-7243
Toll-Free: (800) 241-1044
Fax: (301) 402-0018
TTY: (301) 402-0252
E-Mail: nidcdinfo@nidcd.nih.gov
http://www.nidcd.nih.gov/

National Diabetes Information Clearinghouse
1 Information Way
Bethesda, MD 20892-3560
Phone: (301) 654-3327
Toll-Free: (800) 860-8747
E-Mail: ndic@info.niddk.nih.gov
www.niddk.nih.gov/health/diabetes/ndic.htm