Understanding Diabetes

by Food and Drug Administration (FDA)

That's the message that the American Diabetes Association (ADA) is driving home to millions of people who believe they may be "borderline diabetic," or that their "sugar is just a bit high." Convenient phrases and stereotypes such as these don't adequately describe one of the nation's leading causes of death and disability. In fact, they tend to only minimize problems associated with the disease. The bottom line? An accurate diagnosis is essential, because while a person can live a long and healthy life with diabetes, ignoring it or not taking it seriously can be deadly.

"It's crucial to know when you have diabetes, to hear the diagnosis, and to pay attention to it," says ADA president Christopher D. Saudek, M.D.

Saudek, who also heads up the diabetes center at Johns Hopkins University School of Medicine in Baltimore, says he's seen people deny their diabetes "almost to the point of death."

Diabetes mellitus is a chronic disease in which the pancreas produces too little or no insulin, impairing the body's ability to turn sugar into usable energy. Doctors often use the full name "diabetes mellitus," rather than "diabetes" alone, to distinguish this disorder from diabetes insipidus — a different disease altogether that is characterized by excess urination, but is unrelated to blood sugar.

The number of people diagnosed with diabetes has increased more than sixfold from 1.6 million in 1958 to 10 million in 1997, according to the Centers for Disease Control and Prevention (CDC) in Atlanta. Today, some 16 million people have the disease — making it a leading cause of death in the United States — yet 5 million don't know they have it. And nearly 800,000 new cases of diabetes are diagnosed each year.

There is no cure for the disease, and the resulting health complications from poorly controlled diabetes are what make it so frightening. Consistently high blood sugar levels can, over time, lead to blindness, kidney failure, heart disease, limb amputations, and nerve damage. In fact, diabetes is the leading cause of new cases of blindness in adults between the ages of 20 and 74, and it accounts for 40 percent of people who have kidney failure. Cardiovascular disease is 2 to 4 times more common among people with diabetes, and is the leading cause of diabetes-related deaths. The risk of stroke is also 2 to 4 times higher in people with diabetes, and 60 percent to 65 percent have high blood pressure.

Despite these numbers, Saudek says diabetes can be very well-managed and that people can expect to live full and productive lives. Much of the treatment, however, depends largely on self-care practices. It's important, Saudek says, not only to target good behaviors, but also to consistently follow through with them.

Monitoring blood sugar levels is a key component in treatment and management of the disease. Research has indicated that people who keep their blood sugar levels within individual target ranges set by their doctors stand a good chance of reducing the risk of complications from diabetes. Moreover, in many cases intensive lifestyle changes in diet and exercise actually can prevent, reduce or delay the risk of developing one type of the disease.

Blood sugar, or blood glucose, refers to the amount of sugar in the blood. The brain's only food is glucose; therefore, blood sugar must be maintained at a certain level for the brain to function normally. After eating any meal that contains carbohydrate or protein, a person's blood sugar normally rises, often to between 120 and 130 milligrams per deciliter (mg/dL), but generally not above 140 mg/dL. Every day, every hour, blood sugar levels vary, even in people who don't have diabetes.

If the blood sugar level drops too low (hypoglycemia), a person's ability to reason can become impaired. When the blood sugar levels are too high (hyperglycemia), diabetes is diagnosed. Often the diagnosis is obvious to doctors because symptoms such as thirst, fatigue, weight loss, frequent urination, and persistent vaginal infections in women are evident. In the presence of these symptoms, diabetes can be confirmed by a random test of blood sugar, meaning that the blood is drawn at any time during the day, rather than specifically before eating breakfast. If the person is thirsty and urinating large amounts, the blood sugar usually will be well over 200 mg/dL, sometimes up in the 300s and 400s, or higher.

But when the classic symptoms are not present, the criteria for diagnosing diabetes include a fasting blood glucose test. This means that the blood glucose is drawn at least 10 hours following a meal early in the morning, when it is usually at its lowest point in the day. A random blood glucose higher than 200 mg/dL and a fasting glucose of 125 mg/dL or more confirms a diagnosis of diabetes.

To understand diabetes it's important to know something about insulin. Insulin is a hormone made in the pancreas, a large, elongated gland located behind the stomach. Its purpose is to "unlock" the cells of the body so that glucose carried by the blood can be used for energy. When you eat carbohydrates, your blood sugar rises. This increase triggers a release of insulin from cells in the pancreas called beta cells. The insulin "opens the doors" of the cells throughout the body to glucose. As glucose enters the cells, the blood sugar level falls back to normal — and the release of insulin ebbs until the next time protein or carbohydrates are eaten. The basic problem in type 1 diabetes is that the pancreas quits making insulin. In type 2, it either doesn't make enough or something interferes with the action of the insulin that is made. Someone with type 1 diabetes must inject replacement insulin to stay alive. Blood sugar levels in type 2 diabetes usually are controlled by drugs that lower blood sugar as well as diet and exercise. Sometimes, injections of replacement insulin are needed to maintain normal blood sugars. The increasing emphasis on the importance of reducing weight and other lifestyle changes, combined with the latest advances in medical therapies, all have had dramatic effects on diabetes control.

While it is fairly easy to diagnose, determining what type of diabetes a person has can be both challenging and critical. An accurate diagnosis matters because there are different ways to treat the different types of diabetes in order to stave off potential long-term complications.

About the Author

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