Diabetes is a complex and often-misunderstood disease that affects the way the body produces and uses insulin, a hormone that regulates blood sugar levels. The disease has a number of causes and comes with potentially devastating complications, particularly when it is poorly controlled.
According to the U.S. Department of Health and Human Services the diabetes epidemic is worsening, with a 27 percent increase in incidence the last few years. Unless Americans adopt lifestyle changes—weight management, exercise, healthy diet—this alarming trend will continue. This is particularly worrisome because diabetes can contribute to blindness, kidney disease and heart disease. In fact, complications of the disease were responsible for nearly 70,000 deaths in 2000.
Below, Jacqueline Salas-Spiegel, MD, an endocrinologist at the Naomi Berrie Diabetes Center at Columbia University and assistant clinical professor of medicine in the division of endocrinology, discusses risk factors and treatment options for type 2 diabetes, which is the most common form of the disorder.
What is type 2 diabetes?
Type 2 diabetes is a chronic illness that is defined as an abnormality in the way the body processes glucose. The digestive system breaks down carbohydrates-sugars and starches-to glucose, which the body uses as its primary fuel.
Although the body produces enough insulin, and in some cases, too much insulin, it is unable to efficiently use that insulin to regulate glucose. Blood glucose levels will rise and can cause complications in all organ systems of the body. Diabetes is a major cause of death in this country, either directly through its complications or more indirectly through cardiovascular disease; most people with diabetes will die from heart attack or stroke.
What are the major complications associated with type 2 diabetes?
In patients with type 2 diabetes, the major complications can be put into two groups. There are microvascular and macrovascular complications. That means small-vessel complications and large-vessel complications.
The small-vessel diseases are significantly related to the high blood glucose levels. These complications include what most of us associate with diabetes. The first one is diabetic eye disease, which can cause decreased vision and lead to blindness. The second one is diabetic kidney disease, which can lead to dialysis and is, in fact, the leading cause of dialysis in the US. And the third is diabetic nerve disease, neuropathy, which can lead to amputations of the toes and feet and progressively worsening disease.
The large-vessel diseases, which include heart attack, stroke and peripheral vascular disease, have a variety of causes, not just the blood sugar. They are related to characteristics of the metabolic syndrome such as high blood pressure and high cholesterol. In most patients with diabetes, their cause of death is related to these complications. So most patients do not die of diabetes; they die of heart disease and stroke, but type 2 diabetes is one of the major causative factors of heart attack and stroke.
What causes these complications?
The way that high blood sugar in type 2 or type 1 diabetes, which occurs in children, causes microvascular and macrovascular disease or complications is an area that is still under significant investigation and research, but some key elements are known.
We currently believe that high blood sugar in the bloodstream has the ability to attach to a variety of proteins in the body such as proteins in the eyes and kidneys. This attachment of sugar to these proteins damages them and this leads to weakening of the vessel. For example, in the eye, the attachment causes leakage of fluid and blood into the eye, thereby causing diabetic eye disease. Similar effects happen in the kidneys and in the nerve endings.
What is the primary mode of treatment?
Lifestyle modification is really the cornerstone of treatment for type 2 diabetes. And what that means is diet and exercise or physical activity.
Increasing physical activity is not necessarily about joining the gym or running a marathon. It's really just taking the stairs when you're at your office or at home, walking a little bit longer, gardening. A variety of moderate levels of physical activity and still add up to much improvement in type 2 diabetes.
When medical therapy is indicated we always want the patients to remember that that doesn't mean that they can stop their diet and exercise. Diet and exercise always remains the cornerstone of therapy.
What medical therapy is available?
When a type 2 patient who has been good with their diet and exercise realizes that they need additional help because the blood glucose levels are rising despite their best efforts, the first class of drugs that we use is a class called insulin sensitizers. What we're trying to do is to make the body less resistant to insulin, and this class of drugs can really address that problem at the levels where the resistance takes place, which is in the liver or in the fat or in the muscle.
The next class of drugs that are available for type 2 diabetes is called sulfonylureas. This class of drugs is very different because it allows the pancreas to produce larger amounts of insulin. Sulfonylureas work by stimulating the beta cells of the pancreas. Beta cells are the insulin-producing cells. This insulin is then released into the bloodstream and assists in lowering blood sugar.
Another class of drugs called alpha-glucosidase inhibitors decreases or prolongs the absorption of carbohydrates, meaning starches, from the gut or the intestinal tract. So when people consume carbohydrates, they're not absorbed all at once and they don't raise blood sugar as quickly or as much.
If patients with type 2 haven't achieved their blood sugar goals by using a variety of oral treatments along with diet and exercise, the next step in their treatment is definitely insulin.
What is the outlook for patients with type 2 diabetes?
In most, if not all, patients, type 2 diabetes can be well controlled. There are a variety of clinical studies showing that, if patients control their blood sugar, they will not go on to develop the severe diabetes complications of blindness, amputation and kidney disease . So that's good news.
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