Diabetes mellitus is a metabolic disorder with abnormally high blood glucose levels (hyperglycemia) as its most prominent feature. During intestinal digestion, carbohydrates and proteins are broken down into simple sugars and amino acids, respectively. The liver converts all of the sugars and some of the amino acids into glucose, a simple sugar that is used for energy by every cell in the body.

Glucose passes from the bloodstream into the cells with the help of insulin, a hormone produced by the pancreas (a pear-shaped organ located just below the stomach). By attaching to receptor sites on the surface membrane of a cell, insulin promotes the movement of glucose-transport proteins from the interior of the cell to its surface, where they bind with glucose and carry it into the cell.

In diabetes mellitus, several problems may interfere with this process: pancreatic insulin production may be partially or completely impaired, or body cells may become unable to respond to normal amounts of insulin efficiently.

These underlying problems in fact distinguish the two main types of the diabetes. In type 1 diabetes mellitus, also once known as juvenile diabetes, the pancreas produces little or no insulin. Type 1 diabetes develops suddenly and most commonly affects those under age 30; the average age of onset is between 12 and 14. However, type 1 diabetes accounts for only about 5 percent of cases of diabetes mellitus.

In the much more common type 2 diabetes mellitus, also once known as adult-onset diabetes, insulin production by the pancreas is only moderately reduced, but cells are unable to respond efficiently to insulin—a condition referred to as insulin resistance. The onset of type 2 diabetes is usually gradual and tends to affect people over age 40, particularly those who are overweight. Infrequently, an adult may develop type 1 diabetes.

In both type 1 and type 2 diabetes, the hyperglycemia leads to excretion of glucose in the urine and an accompanying increase in urine production. If inadequate amounts of insulin are administered to patients with type 1 diabetes, unrestrained release of fatty acids from adipose (fat) tissue leads to the overproduction of ketone bodies in the liver. Accumulation of ketone bodies can cause a life-threatening condition known as diabetic ketoacidosis (DKA). DKA may occasionally affect those with type 2 diabetes in periods when the body is highly stressed, for example, during a severe infection.

People with type 2 diabetes are susceptible to another life-threatening condition known as a hyperosmolar nonketotic state, characterized by extremely high blood sugar levels. This condition usually occurs in elderly persons with some other serious underlying illness. An episode of either DKA or the hyperosmolar state may be the first indication that someone has diabetes.

People with diabetes may also suffer from low blood sugar (hypoglycemia) if too much insulin or oral hypoglycemic agent is given for treatment.

After 10 to 20 years of diabetes, patients are at risk of developing complications, such as vision disorders, kidney damage, and peripheral nerve degeneration (neuropathy). Strict control of blood glucose can delay or prevent these complications. Loss of sensation in the feet may allow injuries to go unchecked and become infected.

In addition, people with diabetes are at increased risk for developing narrowing of the coronary arteries as well as narrowing of arteries supplying the brain and legs. The combination of foot infections and decreased blood supply can lead to gangrene (tissue death), which may require amputation. Diabetes mellitus (and its complications) is the fourth leading cause of death in the United States.

Treatment of type 1 diabetes requires between one and four daily injections of insulin. (Insulin cannot be taken by mouth, since digestive juices would destroy it.) In addition, diet and exercise must be planned carefully to ensure that blood glucose levels are neither too high nor too low. Type 2 diabetes may be controlled with a combination of diet, exercise, and weight loss, although medications (including insulin) are usually necessary. Treatment is largely a process of self-management. Although there is no cure, almost all people with diabetes are able to control their symptoms and lead full, productive lives.

Symptoms of Diabetes

• Excessive and frequent urination (as often as every hour or so). Nighttime awakening to urinate is common.

• Increased thirst.

• Increased appetite.

• Unintentional weight loss.

• Blurred vision.

• Fatigue and weakness.

• Recurring or persistent infections of the bladder, skin, or gums.

• Numbness and tingling in feet and hands.

• Symptoms of hypoglycemia (abnormally low blood sugar levels).

• Emergency symptoms of hyperosmolar nonketotic states: extreme thirst, lethargy, weakness, mental confusion, coma.

• Emergency symptoms of diabetic ketoacidosis: nausea and vomiting, labored breathing, mental confusion, coma.

What Causes Diabetes?

• Type 1 diabetes is an autoimmune disorder, resulting from a mistaken attack by the immune system on insulin-producing cells in the pancreas.

• Genetic factors are important in type 2 diabetes.

• Obesity predisposes individuals to the development of type 2 diabetes.

• Certain drugs, such as corticosteroids or thiazide diuretics, may increase the risk of type 2 diabetes.

• Other disorders, such as hemochromatosis, chronic pancreatitis, Cushing’s syndrome, or acromegaly, may lead to diabetes. Surgical removal of the pancreas may also lead to diabetes.

• Pregnant women may develop diabetes (gestational diabetes), which usually disappears after childbirth; these women are at an increased risk for subsequent development of type 2 diabetes.

• Contrary to popular belief, eating lots of foods rich in sugar does not promote diabetes.

Prevention of Diabetes

• To prevent the development of type 2 diabetes, lose weight if you are more than 20 percent overweight, and maintain weight within healthy limits.

• Exercise regularly.

• There is no known way to prevent type 1 diabetes.

• People with either type of diabetes should get regular eye examinations to aid in early detection and treatment of diabetes-related vision disorders.

Diagnosis of Diabetes

• Patient history and physical examination may suggest presence of the disorder.

• Diagnosis is made when fasting blood tests show high glucose levels (126 mg/dL or greater) on at least two occasions.

• When test results are ambiguous, a glucose tolerance test may be done. A drink containing 75 grams of glucose is swallowed and blood glucose levels are measured every 30 minutes over a two-hour period.

• Urine samples may be analyzed for protein content.

• Blood glycohemoglobin is measured; it indicates the average blood glucose levels over the preceding two to three months.

How To Treat Diabetes

For type 1 diabetes:

• Daily injections of insulin are necessary. One to four daily injections are required to control blood glucose levels. Long-acting and rapid-acting insulin preparations are available; a combination of the two kinds is often prescribed.

• A strict diet and schedule of meals are necessary to control blood glucose levels. Your doctor may recommend a diet low in fat, salt, and cholesterol, and may advise you to see a nutritionist for dietary planning.

• Because both exercise and insulin lower glucose levels, exercise and insulin injections must be timed so that they do not combine to cause a dangerous drop in blood sugar (hypoglycemia).

• Strict adherence to the timetable of injections, meals, and exercise is necessary for proper management of the disease.

For type 2 diabetes:

• A diet low in fat and other calories, in addition to regular exercise, is necessary to control weight.

• Oral hypoglycemic drugs, such as tolbutamide, chlorpropamide, tolazamide, acetohexamide, glyburide, glipizide, glimepiride, repaglinide, or meglitonide may be prescribed to increase insulin production by the pancreas, if exercise and diet do not lower glucose levels sufficiently.

• Other oral agents can reduce insulin resistance (metformin, pioglitazone, and rosiglitazone) or slow the absorption of sugars from the intestine (acarbose and miglitol).

• Insulin injections may be necessary in more severe cases of type 2 diabetes, or if a patient with type 2 diabetes contracts an additional illness.

For both types of diabetes:

• Blood tests to measure glucose levels should be performed as your doctor recommends, one to four times a day. Your doctor will recommend a blood monitoring device to use at home.

• Careful attention must be paid to the risk factors for atherosclerosis because of its increased occurrence with diabetes. Those suffering from diabetes should not smoke, should reduce dietary saturated fat, cholesterol, and salt, and should take any medications prescribed for high blood pressure or high cholesterol levels.

• People with diabetes should drink generous amounts of water when stricken with another illness, such as the flu, to replace lost fluid and prevent diabetic coma. When ill, people with type 1 diabetes should test their urine for ketones every four to six hours.

• People with diabetes should practice good foot care and check their feet every day. Nerve damage from diabetes mellitus reduces sensation in the feet, and small foot problems may turn into major infections.

• Laser photocoagulation to prevent the rupture of tiny blood vessels in the eye may help to prevent or treat diabetic retinopathy. Most patients with diabetes need an eye examination by an ophthalmologist at least once a year to detect the earliest manifestations of retinopathy.

• Dialysis, an artificial blood-filtering process, may be necessary to treat kidney failure. In advanced cases a kidney transplant may be advised.

• Amitriptyline, desipramine, or nortriptyline, medications usually used to treat depression, or the anti-seizure medication gabapentin may be prescribed to relieve the pain in the limbs.

• Excellent control of blood glucose levels delays or prevents late complications affecting the eyes, kidneys, and nerves.

• Kidney damage can be slowed by controlling blood pressure and using ACE inhibitors.

• The American Diabetes Association can provide information about support groups in your area.

When To Call A Doctor

• Call a doctor if you notice a sudden or gradual increase in hunger, thirst, and urine output.

• Call a doctor if you have diabetes and an additional illness such as a cold or the flu causes blood sugar levels to go out of control. Do not take over-the-counter medications without first consulting your doctor.

• Emergency: Call an ambulance if a person with diabetes loses consciousness. Inform the doctor or the rescue worker that the person has diabetes.

• Emergency (in type 2 diabetes): Call an ambulance immediately if you develop symptoms of a hyperosmolar nonketotic state; these include extreme thirst, lethargy, weakness, and mental confusion.

• Emergency (in type 1 diabetes): Call an ambulance immediately if you develop symptoms of diabetic ketoacidosis; these include dry mouth, dry and flushed skin, sweet or fruity-smelling breath, labored breathing, vomiting, and abdominal pain, with or without excessive urination and extreme thirst.

• Emergency (in type 1 diabetes): Call your doctor right away if urine tests detect the presence of ketones and the steps given by your doctor fail to control the problem.

For more information on diabetes, click on this link -- Johns Hopkins Health Alerts: Diabetes

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