Obesity is fueling an epidemic of one of the world's most serious chronic diseases: diabetes. In the United States, nearly 21 million people have diabetes today, with 1.5 million new cases being diagnosed each year. People of all ages are at risk, including children, adults and senior citizens.
Treatment and prevention start with understanding the condition, so let's review some basic facts about this complex chronic disease.
The word diabetes refers to frequent urination. There are actually several types of diabetes, all of which share the symptoms of polyuria (frequent urination) and polydipsia (frequent drinking).
The most common type is diabetes mellitus, or "sugar diabetes." The word mellitus is from the Greek "like honey" and means "sweet." This refers to the presence of sugar in the urine of people with diabetes. In diabetes mellitus, the blood level of glucose (the main sugar that our bodies use to produce energy) is too high. Some of this excess sugar winds up in the urine, and that forces more water to be excreted into the urine, resulting in polyuria. Losing all that water via urination naturally causes the person to become dehydrated, which is why people with diabetes are often thirsty and have polydipsia.
Glucose levels in the blood are affected by several different hormones, but one of the most important is insulin, which is produced by the pancreas and works to lower blood sugar levels. There are two types of diabetes mellitus (DM). Type 1 DM sets in when the pancreas becomes unable to produce enough insulin to lower blood glucose to safe levels. By far the most common type of diabetes, however, is type 2 DM, which is due to an inadequate response to insulin in the rest of the body, especially the liver, muscles, and fat cells.
Type 1 DM typically begins during childhood or adolescence, and is sometimes called "childhood-onset diabetes." This is usually an autoimmune disease, in which the insulin-producing cells are attacked by the body's immune system and eventually die off. However, some people don't develop type 1 DM until their 20s or later, sometimes after an injury or illness that damages the pancreas.
Insulin is critically important for normal metabolism, so people with Type 1 DM must take insulin (usually by injection) in order to survive. Because of this, type 1 DM is also sometimes called "insulin-dependent diabetes mellitus," or IDDM.
Although type 2 DM can occur at any time in life, most cases start during adulthood, and so it has been called "adult-onset diabetes." People with this type of diabetes generally have normal or even high levels of insulin, but their bodies gradually become resistant to its glucose-lowering effects. Lifestyle changes (diet and exercise) and oral medications, are often sufficient to control type 2 DM, so type 2 has also be called "non-insulin-dependent diabetes," or NIDDM.
Some people with type 2 diabetes, however, do eventually need insulin to control their sugar levels, a situation that becomes more likely as the disease progresses over time. But even when insulin is part of the treatment, patients with type 2 DM are different from those with type 1 DM. The main difference is that those with type 1 DM must take insulin to survive, while those with type 2 DM need the insulin primarily just to control their blood sugar. Because of these differences, and the possibility of confusion, we generally don't use the terms IDDM and NIDDM anymore.
Some other types of diabetes have nothing to do with blood sugar at all. Patients with diabetes insipidus have polyuria and polydipsia due to a problem regulating urine production. This rare condition is completely different from diabetes mellitus, and it is important not to confuse the two. Usually, when the word "diabetes" is used by itself, it means type 1 or type 2 diabetes mellitus.
In future entries I'll discuss who is at risk for diabetes, how to reduce your risk, and some tips on managing the disease.
