Overview, Causes, & Risk Factors

Diabetes mellitus, often called diabetes, is a condition that makes it hard for the body to control the level of glucose in the blood. This means it is hard for the body to convert food into the energy that the body needs to work. Glucose is the main form of sugar in the body.

What is going on in the body?

The pancreas, a long, thin organ located behind the stomach, makes insulin. In most people, the pancreas makes extra insulin when they eat. It is then released into the bloodstream. Insulin helps move glucose that is in the bloodstream to the inside of cells in the body. Glucose is a key source of energy for the body. In a person with diabetes, the pancreas cannot make enough insulin to keep up with the body's demand. So glucose cannot be moved into the cells and used. In some types of diabetes, the body cells resist the insulin. As a result, glucose builds up in the blood. And that leads to a high blood glucose level, called hyperglycemia.

Some 17 million Americans have diabetes, according to the American Diabetic Association, also known as ADA. There are three main types of diabetes.

Type 1 diabetes. This type used to be known as insulin-dependent diabetes mellitus, IDDM, or juvenile-onset diabetes. A person with this type makes little or no insulin. So he or she needs to take insulin shots each day.

Type 2 diabetes. This type used to be known as noninsulin-dependent diabetes mellitus, NIDDM, or adult-onset diabetes. This is by far the most common type of diabetes. Someone with type 2 diabetes might make healthy or even high levels of insulin. But obesity makes his or her body resistant to its effect. Type 2 diabetes used to be rare in children. But with the increase in obesity in children, doctors are now finding that as many as 1 out of each 20 children who have diabetes has type 2 diabetes. Of these children, 85% are obese.

Gestational diabetes or pregnancy-induced diabetes. This type of diabetes develops in a pregnant woman. In most cases, this type of diabetes goes away after the woman's child is born.

There are other types of diabetes that are less common. This category includes diabetes caused by a genetic defect or pancreatic diseases. Other types of diabetes are caused by hormonal problems or from being exposed to certain drugs or chemicals.

These include:

Diabetes caused by a hormonal imbalance. One example is Cushing syndrome, which involves high levels of adrenal hormones.

Diabetes caused by medicines. These can include prednisone, oral contraceptives

, or thiazide diuretics.

Diabetes caused by other conditions. These include chronic inflammation, infection, or other damage to the pancreas.

What are the causes and risks of the disease?

Genetics may play a part in all types of diabetes mellitus. Other causes and risks vary. They depend on the type of diabetes involved.

Type 1 diabetes does not always have a known cause. Experts believe it might be caused by an autoimmune disorder, in which the body makes antibodies that destroy pancreatic cells. Experts do know that type 1 diabetes is more common in whites than in other groups.

Type 2 diabetes occurs when the cells in the body are resistant to insulin. As a result, the body cannot use blood glucose as well as it should. Risk factors for type 2 diabetes include:

Obesity. This is the main cause of type 2 diabetes in both adults and children. A recent study showed a 33% increase in the number of Americans with type 2 diabetes over the past 8 years. The increase was 70% in people ages 30 to 39 years old and was linked to a sharp rise in obesity in this group.

Race. This type of diabetes is more common in African Americans, Hispanic Americans, Asian Americans, Native Americans, and Pacific Islanders.

Lack of physical exercise. A recent study showed that walking briskly for 30 minutes a day at least 5 days a week reduces a woman's risk of type 2 diabetes.

High blood pressure. Experts define this as a blood pressure equal to or greater than 140/90.

Low HDL level, known as the good cholesterol, and high triglyceride level. HDL levels equal to or less than 35 mg/dL and/or a triglyceride level greater than or equal to 250 mg/dL are considered unhealthy.

Age of 45 or older.

History of gestational diabetes, or having babies that weighed more than 9 pounds at birth.

Hormonal changes linked to menopause. A recent study of 16,000 American women between the ages of 40 and 65 showed that diabetes was one of the top six diseases diagnosed. A long-term study is under way to see if menopause and changes in hormone level are factors in the development of type 2 diabetes. Gestational diabetes is considered when a woman has any abnormal glucose test result during pregnancy. It may be the result of increased hormone levels during pregnancy, which work against insulin. Weight gain during pregnancy might also be a factor in causing gestational diabetes.

Almost all people who develop type 2 diabetes have a condition called pre-diabetes first. This condition used to be known as impaired glucose tolerance or impaired fasting glucose, and the ADA estimates that almost 16 million people over the age of 40 have it. This condition occurs when blood glucose levels are higher than healthy levels but too low to be diagnosed as diabetes. Without lifestyle changes, most people who have pre-diabetes will progress to type 2 diabetes within 10 years.

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Symptoms & Signs

What are the signs and symptoms of the disease?

Symptoms partly depend on the type of diabetes a person has and how long it has been untreated. Many patients with type 2 diabetes have no symptoms at all. Any signs and symptoms are mostly related to high blood glucose levels and include:

bladder infections

coma, which happens only if the diabetes gets too far out of control

extreme hunger

extreme thirst

fatigue and weakness

frequent urination in increased amounts

nausea and vomiting

skin infections, especially fungal or more serious bacterial infections

visual problems, such as blurred vision

weight loss despite increased hunger and thirst

A condition called ketoacidosis may occur in a person with type 1 diabetes if the person goes without enough insulin for too long. This is a severe complication and requires medical attention right away. Symptoms include:

deep rapid breathing, sometimes with a fruity odor to the breath

drowsiness

extreme thirst

frequent urination

nausea and vomiting

stomach pains

upset stomach

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Diagnosis & Tests

How is the disease diagnosed?

A doctor may suspect diabetes after taking a person's health history and doing a physical exam. Based on those results, the doctor may want to check for a high glucose level in the blood. There are several types of blood tests doctors can use to diagnose diabetes, including:

fasting plasma glucose test, which is the most common method to diagnose most cases of diabetes. In this test, a person is asked to fast overnight for at least 8 hours. In the morning, the level of glucose in the blood is then checked. Healthy fasting plasma glucose levels are less than 110 milligrams per deciliter or mg/dL. A fasting plasma glucose level of more than 126 mg/dL usually suggests diabetes. Levels between 110 and 126 mg/dL are seen in pre-diabetes.

oral glucose tolerance test which is the preferred way to diagnose gestational diabetes. It can also be used to diagnose type 2 diabetes and pre-diabetes. In this test, a person is asked to drink a sweet liquid. Blood samples are then drawn at timed intervals. If a person does not have diabetes, the glucose levels will rise and then fall quickly after drinking the sweet liquid. When a person has diabetes, glucose levels will rise higher and fail to come down as fast as those in a person without diabetes. If the blood glucose level is 140 to 199 mg/dL 2 hours after drinking the liquid, a diagnosis of pre-diabetes can be made.

plasma glucose test, which can be done without fasting and is used as a screening tool. A level of 200 mg/dL or higher suggests diabetes. If the level is above 200 mg/dL, a fasting glucose test or oral glucose tolerance test can be done to confirm the diagnosis of diabetes.

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Prevention & Expectations

What can be done to prevent the disease?

There is no way to prevent type 1 diabetes. But it may be possible to prevent type 2 diabetes in many cases! This is especially true once pre-diabetes is known. Even modest lifestyle changes can help prevent the onset of diabetes. This is why it is very important to recognize pre-diabetes. The key is to:

eat a healthy diet

exercise 30 minutes a day at least 5 days a week

maintain a healthy body weight

What are the long-term effects of the disease?

Over time, high blood sugar levels damage blood vessels, nerves, and other internal structures. Long-term effects of diabetes may include:

Retinopathy, a disease in the retina of the eye that can cause blindness. Diabetes is the number one cause of blindness in adults who are younger than age 40.

Diabetic nephropathy, which is a disease of the kidneys. This disease can progress to a form of kidney failure known as chronic renal failure. Diabetes is the leading cause of chronic renal failure.

Atherosclerosis, also known as hardening of the arteries. Artherosclerosis can lead to heart attacks and strokes. It can also cause poor circulation in the legs and feet.

Diabetic neuropathy, which means damage to nerves in the arms and legs. This damage can cause numbness and pain in the hands and feet. When combined with poor circulation, neuropathy can result in diabetic foot ulcers and leg infections that may require amputation.

Autonomic neuropathy, which is a disorder that affects certain nerves. It may cause problems with digestion, diarrhea, erectile dysfunction, a rapid heartbeat, and low blood pressure.

Some of these long-term effects may begin even at the moderate-high levels of blood glucose seen in pre-diabetes. This is why it is important to eat a healthy diet, exercise 30 minutes a day, and keep body weight within a healthy range. All of these actions can keep blood glucose within healthy levels. People with diabetes risk factors should also be screened for pre-diabetes on a regular basis.

What are the risks to others?

Diabetes is not catching and poses no risk to others. It does tend to run in families.

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Treatment & Monitoring

What are the treatments for the disease?

Treatment depends on the type of diabetes that is present. A person with type 1 diabetes will most likely need insulin shots each day. These shots replace the insulin that the pancreas cannot make on its own. A proper diet is also a key to staying healthy.

Gestational diabetes is also usually treated with diet and insulin shots as needed.

The most effective treatment available for type 2 diabetes is a change in lifestyle, including the following:

Weight loss. Loss of as little as 10 to 15 pounds can help keep blood glucose under control.

Healthy eating. A healthy diet can help with weight loss. And that can prevent the need for medicine.

Regular exercise. Walking only 30 minutes a day can lead to better glucose control.

A person with type 2 diabetes may also be treated with oral medicines and/or insulin shots. Diabetes pills can work in four ways.

They can stimulate the pancreas to make more insulin.

They can help the cells in the body use insulin and glucose better.

They can keep the starches that are eaten from being broken down into glucose in your intestines.

They can reduce the amount of glucose that is released from the liver.

Treating the underlying condition or stopping a certain medicine may correct diabetes that is caused by medicine or an illness. If this is not possible, diet, exercise, and pills or shots are used to control the blood glucose.

Careful monitoring and management help keep diabetes under control and reduce the risk of long-term effects. A person with diabetes should:

monitor his or her blood glucose levels at home

take medicines as prescribed by the doctor

know how to recognize and treat hypoglycemia, which is low blood glucose

get regular eye checkups that include an examination of the retina after the pupil of the eye has been dilated with eye drops

do thorough foot care on a daily basis

follow a plan to monitor and treat changing blood glucose levels when sick or under stress

follow a healthy diet

have regular checkups with the doctor

get a pneumonia shot

get a flu shot each fall

Treating the complications of diabetes may involve many different specialists. For example, a person with diabetes may need to see eye, heart, foot, hormone, and circulation specialists. Dieticians also help people with diabetes by designing a healthy eating plan. Dieticians can also suggest healthy calorie intake levels and types of foods to eat.

What are the side effects of the treatments?

Side effects depend on the treatments used. If a person has too much insulin in his or her body, the blood glucose levels can drop too low. This condition, called hypoglycemia, can cause the following symptoms:

confusion

hunger

nausea

nervousness

shakiness

sweating

The usual treatment for low blood glucose is to drink a sweet beverage or eat a sweet food. If low blood glucose goes untreated, a person may pass out or have seizures. Emergency medical care is crucial in this situation.

Some of the oral medicines used for type 2 diabetes may cause weight loss or gain, allergic reactions, or liver damage. Some may also cause low blood glucose levels.

What happens after treatment for the disease?

Diabetes generally cannot be cured, but it can be controlled with careful management and treatment. A person with diabetes will need to have close medical follow-up throughout his or her life to control blood glucose levels and prevent serious complications.

How is the disease monitored?

A person with diabetes should keep all of his or her appointments with his or her primary doctor, as well as other scheduled specialists. Physical exams, blood tests, urine tests, foot and skin care, routine eye exams, and routine dental care are all part of basic care for a person with diabetes. The main goal of treatment is to keep blood glucose levels as close to a healthy range as is safely possible. In general, ideal ranges of blood glucose levels are 80 to 120 milligrams per deciliter (mg/dL) before meals and 100 to 140 mg/dL at bedtime. Any new or worsening symptoms should be reported to the doctor.

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