Type 2 Epidemic
(The Boston Globe, July 25, 2000)
Talk about a letdown.
In all the hype about Viagra, the 53-year-old Washington-area government contractor hadn't heard that the pill doesn't always work. He discovered this fact, to his great dismay, on what was supposed to be a special night with his new girlfriend. It turned out that this man - who asked that his name not be used - was one of the 5.4 million Americans who have Type-2 diabetes but have never been diagnosed.
Long associated with obesity and a sedentary lifestyle, Type-2 diabetes often has been viewed as less serious than its Type-1 cousin, often called juvenile diabetes, in which patients require regular insulin shots to survive. But the contractor painfully learned that Type-2 - or adult-onset - diabetes is closely connected both to heart disease and a host of other problems, such as erectile dysfunction, which even Viagra may not cure.
"It's the great silent disease," said Dr. Evan M. Benjamin, an internist at Baystate Medical Center in Springfield. Indeed, the incidence of Type-2 diabetes has skyrocketed to epidemic numbers in recent years, rising sixfold in the last four decades even as the age of those diagnosed has become younger and younger. But that explosive growth shouldn't be surprising, specialists say, because 90 to 95 percent of cases are related to being overweight - a huge problem in the United States.
In recent years, physicians have become more aware that Type-2 diabetes isn't mild diabetes. Moreover, they increasingly have come to understand that Type-2 diabetes is part of a much larger syndrome, which could underlie as much as 75 percent of all heart disease in the developed world. Consequently, physicians have become more aggressive in treating patients who already have been diagnosed.
But, they haven't been as aggressive in seeking out patients who may have diabetes and don't know it. Although some physicians do test blood sugar as part of a checkup, diabetes screening is not an established routine medical practice. "Chances are the average adult has not been screened for diabetes," said Benjamin, who chairs Massachusetts' Diabetes Control Program advisory board.
On average, most people won't discover they have Type-2 diabetes until five to seven years after it has begun, by which time a lot of damage will have been done. And the damage can be substantial: Diabetes is the leading cause of blindness, kidney failure and amputations not related to injuries, and people with diabetes are two to four times more likely than the rest of the population to have heart disease and strokes.
One out of every 10 US health care dollars, or about $105 billion a year, is spent on diabetes and its complications, most of that on Type-2 diabetes, which makes up 95 percent of all cases.
But, while the two types of diabetes can be equally damaging, they differ in important ways. In Type-1, the pancreas stops making insulin, the key hormone that allows sugar from food, in the form of glucose, to enter cells to be burned for energy or stored for later use. Without insulin, the glucose stays in the blood and the cells essentially starve. As a result, Type-1 diabetes is hard to miss: Symptoms, which usually begin in childhood or early adulthood, include extreme thirst, frequent urination, fatigue, nausea, weight loss and blurred vision. Coma and even death may result if insulin treatment isn't started immediately.
Type-2 diabetes is much less obvious because the body's insulin-making machinery hasn't broken down entirely. Rather, the cells don't use insulin properly. And the symptoms, though similar, are usually less extreme, making them easier to miss.
Although not everyone who is overweight will get diabetes, gaining weight increases the risk because it makes the cells more resistant to insulin. The greater the body weight, the more the pancreas has to crank up its insulin production to overcome that resistance. It's not clear why, but in some overweight individuals, the pancreas can't keep up the pace. Insulin production subsides, and blood sugar levels gradually rise. If nothing is done, over a period of months to years, the blood sugar level can reach diabetic levels.
And, as US children have become increasingly overweight, the number of children with Type-2 diabetes has increased dramatically. Almost unheard of a few years ago, Type-2 is believed to be responsible for 20 percent of all childhood diabetes. "Physicians are now seeing younger patients with Type-2 diabetes who have the same chronic complications as Type-1 patients," said Benjamin of the Massachusetts diabetes program. "It's been a wake-up call for doctors."
Another reason for the increased attention to Type-2 diabetes is a new understanding that high blood sugar is only one facet of a much larger syndrome tied to insulin resistance, which could underlie most heart disease.
Researchers now speak of an insulin resistance syndrome, whose hallmarks include obesity, high blood pressure, and what doctors call "dyslipidemia," which is a combination of low blood levels of HDL, or good cholesterol, and high levels of the fat-storage particles called triglycerides. It also includes an inability to properly process blood sugar, called glucose intolerance, which may eventually lead to Type-2 diabetes.
"It's fair to say that obesity, insulin resistance, hypertension, and abnormal lipids tend to run together," said Dr. David M. Nathan, director of the Diabetes Center at Massachusetts General Hospital. But, he said, "Not everyone has every feature. Some people just have hypertension and obesity. Some have obesity and glucose intolerance. There isn't just one thing going on; there are many things. We're still trying to sort it all out. Nobody really understands it."
However the syndrome is defined, it's very common. As much as one-third of the entire US population has one or more features of the insulin-resistance syndrome. In certain ethnic groups, the proportions are much higher. Nearly all members of the Pima Indian tribe of Arizona, for example, have insulin resistance and half have Type-2 diabetes.
The Washington contractor had several symptoms of insulin-resistance syndrome. While not obese, he had been putting on weight over the years. He also has high cholesterol. His physician started him on blood pressure medication back in 1991, but he soon stopped taking it because the drug made his ankles swell. By the time he saw the doctor again in 1995, his blood pressure had soared to dangerous levels. "He was surprised I was still standing," the contractor said.
Still, he wasn't tested for diabetes until two years later. (He sees a different doctor now).
Why is insulin resistance so common? Researchers theorize that the answer lies in a gene that helped humans survive in a far different environment. Back when humans were hunter-gatherers, having to expend a lot of energy to find their next meal, it was advantageous to have a gene that allowed bodies to store fuel for times when food was scarce. In the developed world, there's no scarcity of food - especially high-fat food - and most people don't have to burn many calories to get it. Now, that same gene that once hoarded fuel for lean times is making us fat, insulin-resistant, diabetic, and heart-diseased.
"As we've become more industrialized," said Nathan of Mass. General, "all components of insulin resistance have become more common. It's a recipe for disaster."
Evidence suggests that even before insulin resistance reaches diabetic levels, cardiovascular risk increases. Studies of people with slightly elevated blood-sugar levels have shown that they have rates of heart disease in between those of people with normal blood sugar and those with diabetes. "Even in prediabetes, you start seeing an accumulation of risk factors," Nathan noted.
When the blood sugar finally crosses the line and becomes diabetes, a whole new set of complications begins: High blood sugar itself can damage the small blood vessels of the eyes, kidneys and other organs, as well as the nerves.
Erectile dysfunction, resulting from both blood vessel and nerve damage, is often one of the first complications to occur in diabetic men. In fact, it's already present in one in five men at the time diabetes is diagnosed.
Because so much damage typically happens before symptoms start, the American Diabetes Association recommended in 1997 that everyone be screened beginning at age 45, and every three years thereafter. The group also advised screening for younger people with risk factors, such as obesity or a family history of diabetes.
Other groups, however, do not endorse the idea of screening people who don't have symptoms. The American Academy of Family Physicians and the American Society for Internal Medicine-American College of Physicians both argue that there's not enough evidence to support the estimated $1 billion cost of such widespread testing. "Unfortunately, there is no good data yet that proves that screening for diabetes improves outcomes," said Dr. Vincenza Snow, senior medical associate at the internist group.
But Dr. Claresa Levetan, a Washington-based endocrinologist, strongly disagrees. "We may never have the evidence, but look at the facts,"said Levetan, director of diabetes education at Washington Hospital Center-Medstar Health. "Women over the age of 65 are three to four times more likely to die of diabetes than of breast cancer. There is now evidence that diabetes is preventable and even reversible if it's caught early enough." ###
Copyright © Miriam Tucker. All rights reserved.