DIABETES How to Cut Your Risk

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"Diabetes rates rose a striking six percent among adults in 1999," the Centers for Disease Control and Prevention (CDC) declared in January. That jump followed a 33 percent increase from 1990 to 1998.

The news came as no surprise to experts.

"There's been an exponential rise in obesity, and I would expect diabetes to follow right along," says Maureen Harris, an epidemiologist at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) in Bethesda, Maryland.

In fact, the percentage of Americans who have diabetes has been rising for decades. "There's been a three-fold increase in the last 40 years," says Harris. And that doesn't account for the aging of the population, which boosts not just the percentage, but the number of people with diabetes.

The first signs of the problem surfaced in 1980, when the National Health and Nutrition Examination Survey first started measuring blood sugar levels in a large sample of Americans.

"Our response was, 'Wow! A lot of people who look totally well are running around with high blood sugar,'" says Harris.

But it wasn't until three years ago that the NIDDK and the CDC launched the National Diabetes Education Program. "We're where we were in the 1970s with high blood pressure," says Harris. "We're trying to alert the public and the medical profession to the fact that there are huge numbers of undiagnosed and untreated diabetics."

The program's first goal is to help keep blood sugar levels stable and sufficiently low in people who have already been diagnosed with diabetes.

"Roughly 55 percent of patients do not have their diabetes under control," says Harris.

Only after that percentage drops, says Harris, "will the National Diabetes Education Program focus on finding undiagnosed patients."

That's critical because, left untreated, the disease takes a tremendous toll.

High Blood Sugar
Heart disease, stroke, blindness, amputations, kidney failure, nerve damage, gum disease, and possibly dementia. Diabetes raises the risk of all these and more (see "The Damage Report," p. 4).

"Once you have diabetes, there's not much--except cancer--that you're not at higher risk for," says Harris. "It's a multi-system disease because glucose is everywhere in the body."

Type 2 diabetes, which accounts for at least 90 percent of diabetes in the U.S., occurs when the body can't make enough--or can't properly use--insulin. (In type 1 diabetes, the body makes no insulin at all.)

Insulin is the hormone that allows sugar in the blood to enter cells, where it's stored or burned for fuel. Without enough working insulin, levels of blood sugar, or blood glucose, rise (see "Blood Sugar: Going Up," p. 5).

It's high blood sugar that causes blindness, kidney disease, and nerve damage. Experts call them "microvascular" complications because they involve small blood vessels.

"There's a clear relationship between eye, kidney, and nerve problems and a fasting blood sugar level of 126 or higher," says Frank Vinicor, director of the CDC's diabetes program. "The higher the blood sugar levels--and the longer they're high--the worse the damage. But damage is very unlikely below 126."

How does high blood sugar cause harm? "The theory with the most credibility is that the glucose attaches permanently to proteins in the retina, kidney, and small blood vessels," explains Vinicor. "These protein- glucose linkages cause the proteins to function abnormally."

In 1997 the American Diabetes Association (ADA) lowered the cutoff for diagnosing diabetes from a fasting blood sugar of 140 to 126. "We realized that even for microvascular complications, a fasting blood sugar of 140 was too high," explains Vinicor.

At the same time, the ADA decided that doctors could use fasting blood sugar levels to diagnose diabetes. Until then, they were supposed to use a "glucose tolerance test," which meant that patients had to drink a sweetened beverage and then wait two hours to get their blood sugar tested. "The procedure was so cumbersome that doctors just weren't doing it," says Harris.

The ADA now advises anyone aged 45 or older to get a fasting blood sugar test once every three years, and more often if they are at high risk (see "Who's at Risk?" p. 8). But a fasting blood sugar under 126 doesn't mean that you're in the clear. New studies suggest that millions of adults have blood sugar levels that are too low to be called diabetes but too high to be called healthy.

Above-Optimal Blood Sugar
Diabetes and its microvascular complications (like blindness) may start when fasting blood sugar levels hit 126, but the macrovascular complications--that is, the damage to large blood vessels--seem to start at lower levels.

"Until recently, people said you either had diabetes or you didn't, and if you didn't, they weren't too concerned," says Hertzel Gerstein, an endocrinologist at McMaster University in Hamilton, Canada.

"But the blood sugar criteria currently used to differentiate people with and without diabetes is based on the risk of eye and kidney disease. There's no reason to think that it also applies to the risk of cardiovascular events like heart attack and stroke."

In fact, Gerstein found that those risks started to climb when blood sugar levels rose above 75.(n1) A new study of more than 4,600 men in Norfolk, England, produced similar results, though it used a long-term measure of blood sugar called glycated hemoglobin (see "Future Test: Glycated Hemoglobin," p. 5).(n2)

The shocker: While only five percent of the men in the British study had glycated hemoglobin levels in the diabetic range, 70 percent had levels that raised their risk of heart attack and stroke.

"All but 25 percent of the population we studied had above-optimal levels of blood sugar," says study co-author Kay-Tee Khaw, a professor of clinical gerontology at the University of Cambridge School of Clinical Medicine in England. "It's a population-wide problem, just like high blood pressure and high cholesterol."

Yet most people assume that as long as they don't have diabetes, their blood sugar is normal. "We can't be complacent about elevated blood sugar levels that don't reach the diabetic range," says Gerstein. "It's like blood pressure levels that used to be considered normal, but now we know are high."

"More and more people know how low their blood cholesterol and blood pressure should be," says epidemiologist Deborah Wingard of the University of California at San Diego School of Medicine in La Jolla. "They should also know what a good blood sugar is."

"Good" means below 110. "But there's nothing magic about these numbers," explains Wingard. "The higher your blood sugar, the higher your risk."

That's not to say that people should panic about their blood sugar, she adds. "But if you go for a checkup and your blood sugar is slightly elevated, and all you find out is that you don't have diabetes, you might mistakenly wait five years for another test."

Researchers don't know exactly how above-optimal blood sugar raises the risk of heart attack and stroke.

"Glycated proteins may make blood vessels more rigid," says Khaw. Too much blood sugar may also alter the protein in low-density lipoproteins, or LDL. "The glucose may turn large, fluffy LDL ['bad'] cholesterol into the more dangerous small, dense LDL," explains Vinicor.

It's also possible that high blood sugar doesn't cause heart attacks and strokes at all. "It may just be a marker for insulin resistance," suggests Khaw. That's when cells are resistant to insulin's action, so the hormone doesn't work properly (see "Blood Sugar: Going Up," p. 5).

People with insulin resistance often have a constellation of risk factors--obesity, high triglycerides, high blood pressure, and low HDL ("good") cholesterol--that are known as "Syndrome X" (see cover story, March 2000). Insulin resistance, not high blood sugar, may be what raises the risk of heart disease and stroke.

Regardless of how high blood sugar harms blood vessels, researchers know what to do about it.

"We know that if we give people statin drugs to lower cholesterol or drugs to lower blood pressure, they will lower the risk of cardiovascular events," says Khaw. That's equally as--if not more--important as lowering their blood sugar. "But it's not feasible to put everyone with elevated blood sugar--75 percent of the adult population--on medication."

Instead, most people need to change their lifestyles. "The vast majority of the population should eat more fruits and vegetables, maintain more-optimal body weight, and increase physical activity," says Khaw. If we could lower average blood sugar levels slightly, "it would lower the risk of cardiovascular disease and diabetes across the population."

Low-Risk Strategy
Here's how to lower your blood sugar level to the optimal range ... or how to keep it there:

1. Watch your weight. If you're a typical American, your risk of diabetes is already elevated.

"In the U.S., men and women of average weight have double the risk of diabetes compared to people with optimal weight," says Harvard's JoAnn E. Manson. "Optimal weight is at least ten percent below the average American's weight."

The average American woman is 5'4" tall and weighs 152 pounds. Her optimal weight is 128 pounds, which would give her a BMI of 22 (see "Rate Your Weight"). The average man is 5'9" tall and weighs 180 pounds. Ideally, he should weigh 150 pounds.

But getting the population's average BMI down to an optimal 22 or less isn't realistic, says Manson. "We're not trying to make everyone lean," she explains. "With 97 million Americans overweight or obese, it's tough enough to get the population's average BMI below 25."

What's more, the risk of heart disease, stroke, and most other health problems doesn't climb until your BMI exceeds 25. "Diabetes is the health condition most strongly linked to a BMI between 22 and 25," notes Manson.

2. Stay off the couch. No matter how much you weigh, "exercise will go a long way toward reducing the risk of diabetes," says Manson.

And it doesn't have to be strenuous, continuous, time-consuming, or expensive,(n3,n4) "In several studies, any moderate exercise--even brisk walking--for 30 minutes a day lowered the risk of diabetes by about 30 percent," notes Manson.

Vigorous exercise probably cuts the risk further, she adds, "but it's hard enough to get people off the couch to do moderate exercise."

And that same 30 minutes a day can help prevent heart disease, stroke, osteoporosis, and possibly breast and colon cancer, says Manson. "Staying active has a tremendous benefit because it reduces the risk of so many diseases."

3. Eat wisely. When it comes to your risk of diabetes, how much you eat matters more than what you eat. But some foods do appear to lower the risk. S

"Whole grains seem to be protective, possibly because they're higher in fiber and magnesium," says Manson. What's more, potatoes and refined grains like white bread increase blood sugar quickly. And that's not good.

"Fruits and vegetables are also great because they're high in magnesium, potassium, and fiber," she adds. And those foods may help protect against obesity because they fill you up without too many calories.

How fats affect the risk of diabetes is still unclear. "Saturated and trans fat may be particularly detrimental," says Manson, "while mono-and polyunsaturated fats may lower the risk."

"But that doesn't mean you can pour on the olive or canola oil," she cautions. "If you're at risk of diabetes, it's best to maintain a low-fat diet because all fats are calorie-dense."

Just don't assume that a low-fat diet means unlimited quantities of low-fat cakes, cookies, and ice cream, or even bread, potatoes, and pasta. The idea is to spend your carbohydrates on vegetables, fruits, and whole grains, which could also cut your risk of cancer, heart disease, and stroke.

Says Manson: "Preventing diabetes really comes down to lifestyle modifications like maintaining a healthy weight, staying physically active, and eating a heart-healthy diet."

(n1) Diabetes Care 22: 233, 1999.

(n2) British Medical Journal 322: 1, 5, 2001.

(n3) J. Amer. Med. Assoc. 282: 1433, 1999.

(n4) J. Amer. Med. Assoc. 268: 63, 1992.

(n5) Amer. J. Pub. Health 90: 1409, 2000.

THE BOTTOM LINE
To cut your risk of diabetes:
Lose weight if you're overweight.
Walk briskly or engage in some other physical activity for at least 30 minutes a day.
Eat whole-grain breads and cereals instead of refined breads, cereals, and sugars.
Eat more fruits and vegetables (other than white potatoes).
Starting at age 45, get your fasting blood glucose level tested every three years--earlier and more frequently if you have risk factors (see "Who's at Risk?" p. 8).
If your fasting blood glucose consistently exceeds 110 mg/dL, use diet and exercise and, if necessary, drugs--to keep your blood pressure and cholesterol at optimal levels.
THE DAMAGE REPORT
"As of 1997, the total direct and indirect cost of diabetes was roughly $100 billion a year," says Frank Vinicor of the Centers for Disease Control and Prevention.

"The major direct costs are due to hospitalization for coronary heart disease and kidney disease," he explains. "But blindness and amputations take the greatest toll on the quality of life." Indirect costs pile up when people are disabled and die prematurely.

The cost of diabetes can be cut by preventing its chief complications:

• Heart Disease and Stroke. The risk of heart disease and stroke is two to four times higher in people with diabetes than in people without the disease. Heart disease is the leading cause of death for diabetics. And an estimated 60 to 65 percent of people with diabetes have high blood pressure, which raises the risk of both heart attack and stroke.

"We need to aggressively treat high blood pressure and high cholesterol in people with diabetes," says Deborah Wingard of the University of California at San Diego School of Medicine.

Kidney Disease. Diabetes is the leading cause of kidney failure, accounting for about 40 percent of new cases. "ACE-inhibitors--drugs that lower blood pressure--can prevent the progression of kidney disease," says Vinicor. "We could prevent half the cases of kidney failure with early treatment."
Blindness. Diabetes is the leading cause of new cases of blindness in people aged 20 to 74. Each year, 12,000 to 24,000 Americans lose their sight because of diabetes. They needn't.
"If the physician sees changes in the back of the eye indicating progressive damage to the retina, we can use photocoagulation--laser treatment--to stop the bleeding, which stops the loss of vision," says Vinicor. "That and getting blood pressure and blood glucose under control could prevent 90 percent of the cases of blindness due to diabetes."

• Nerve Damage and Amputations. About 60 to 70 percent of people with diabetes have mild to severe forms of nerve damage, which can cause slowed digestion, carpal tunnel syndrome, and numbness in the feet or hands.

"Nerve damage can cause people to lose sensation in their feet," explains Vinicor. "If a foot becomes injured, they may not be aware of it. And the resulting foot ulcer can lead to amputation."

Each year, an estimated 67,000 amputations are done in the U.S. on people with diabetes. Early treatment could prevent half of them, says Vinicor.

"We can use a monofilament to detect the loss of sensation in the foot," he explains. "Sometimes all it takes is a pair of running shoes to protect the feet from damage."

Cognitive Decline. Thinking ability appears to deteriorate more quickly with age in people with diabetes, especially if they also have high blood pressure. "This is a relatively new observation," says Vinicor. "We need larger studies to see if it's true and, if so, if the decline is due to accelerated atherosclerosis and stroke or if there's something peculiar about the diminished cognitive function in diabetes."
Other Complications. Periodontal (gum) disease is more common and more severe among people with diabetes, who are also more likely to die of infectious illnesses like the flu or pneumonia. And the risk of birth defects is higher in the children of women who have diabetes.
FUTURE TEST: GLYCATED HEMOGLOBIN
When you get a fasting blood sample taken, it tells your doctor how high your blood sugar was that day. But what about other days?

A blood test for glycated hemoglobin, which is also called hemoglobin A1c or glycosylated hemoglobin, gives a longer-term read on your blood sugar. (Hemoglobin is the component of red blood cells that carries oxygen.) "Glucose attaches to the hemoglobin in red blood cells and stays there for several months," explains Maureen Harris of the National Institute of Diabetes and Digestive and Kidney Diseases.

Right now, doctors use glycated hemoglobin only to monitor people who already have diabetes. They try to keep levels below 7, which means that seven percent of the patient's hemoglobin A1c has glucose attached to it.

But they don't use glycated hemoglobin to diagnose diabetes, because laboratories are not all using the same methods to measure it. That could soon change.

"Right now, one lab may do it differently than others," says Frank Vinicor of the Centers for Disease Control and Prevention. "But probably within a year, the CDC will certify 90 percent of the labs in the U.S. to analyze glycated hemoglobin."

In a recent British study, a glycated hemoglobin under 5 was considered optimal. "Glycated hemoglobin shows great promise in becoming the diagnostic method for diabetes in the U.S.," says Harris. Until then, shoot for a fasting blood glucose of 75 or lower.

BLOOD SUGAR: GOING UP Normal
The rise in blood sugar after a meal stimulates the pancreas to secrete insulin, a hormone that enables the sugar to enter muscle and fat cells, where it is stored or burned for energy.

Insulin Resistance
The pancreas secretes sufficient insulin, but the insulin doesn't do its job very well. To compensate, the pancreas secretes more. The excess insulin manages to keep blood sugar levels within the normal range. But the high insulin is often accompanied by high triglycerides, high blood pressure, and low HDL ("good") cholesterol, all of which raise the risk of heart attack and stroke.

Type 2 Diabetes
The pancreas secretes sufficient insulin, but the insulin doesn't do its job very well. To compensate, the pancreas secretes more, but not fast enough to keep blood sugar from rising to levels (over 125) that raise the risk of eye, kidney, and nerve damage. People with diabetes also have a higher risk of heart attack and stroke. Over time, the pancreas loses the ability to secrete insulin.

NO ONE DIET FOR DIABETES
If you've already been diagnosed with type 2 diabetes, right diet and exercise can prevent problems,

Lose excess weight. You don't have to be a fashion model to get your blood sugar under control. In one study, losing more than 15 pounds helped keep blood sugar levels in check.
Move more. Exercise can help control diabetes, even if you don't lose a pound. The American Diabetes Association recommends 20 to 45 minutes of aerobic exercise at least three days a week(though it cautions patients to use proper footwear, to inspect their feet daily and after exercise, and to avoid exercise in extreme heat or cold and during periods when their blood sugar is poorly controlled).
Eat a DASH diet. To keep your blood pressure from rising, eat a daily diet that contains eight to ten servings of fruits and vegetables, two to three servings of low-fat dairy products, and less than 2,400 mg of sodium (see "The DASH Diet," cover story, December 2000).
Minimize saturated and trans fat. To lower your LDL ("bad") cholesterol and your risk of heart disease, limit red meats, cheese, ice cream, milk, cakes, pies, and other pastries (unless they're low in fat), as well as fried foods like chicken, fish, and potatoes (unless they're fried in unhydrogenated oil).
Choose between unsaturated fats and carbohydrates. Once you get enough fruits and vegetables and low-fat protein foods, your remaining calories can come from any combination of unsaturated fats (like vegetables oils, nuts, avocados, and salad dressings) and carbohydrates (breads, cereals, pasta, rice, and sweets).
Just beware: all fats are high in calories. And too many carbs, especially sugars, can boost your triglycerides. Choose whole-grain over refined carbs to get more fiber, magnesium, and phytochemicals.

RATE YOUR WEIGHT
Are you overweight? One way to find out is to check your Body Mass Index (or BMI), which gauges your weight in relation to your height. Find your weight at the bottom of the graph. Go straight up from that point until you come to the line that matches your height Then check to see which group you fall into.

But this chart doesn't tell the whole story. Although a BMI between 18.5 and 25 is considered "healthy," the risk of diabetes starts to climb above a BMI of 22, especially for women. One other caveat: BMI shouldn't be used to evaluate the weight of children, the frail elderly, serious bodybuilders, or pregnant or breastfeeding women. If your extra weight comes from muscle, not fat. you may have a high BMI even though you're healthy. Frail or older people may have a low BMI even though they're unhealthy,

Source: adapted from Dietary Guidelines for Americans, 2000, U.S. Department of Agriculture and U.S. Department of Health and Human Services.

WHO'S AT RISK?
The more of these risk factors you have, the greater your chances of getting diabetes:

You're over age 45.
You have a family history of diabetes (a parent or sibling with the disease).
Your BMI is 25 or more (see "Rate Your Weight," p. 7). (The risk of diabetes starts to climb at a BMI of 22,)
You don't exercise regularly.
You are African-American, Latino, Native-American, or a Pacific Islander.
Your blood pressure is 140 over 90 or higher.
Your HDL ("good") cholesterol is 35 or lower.
Your triglycerides are 250 or higher.
You've been told that you have impaired fasting glucose (fasting glucose between 110 and 125).
You're a women who had gestational diabetes or who gave birth to a baby weighing 9 pounds or more.
You're a woman with polycystic ovary syndrome.
Source: Adapted from American Diabetes Association.

WARNING SIGNS
Type 1 Diabetes
Frequent urination

Unusual thirst

Extreme hunger

Unusual weight loss

Extreme fatigue

Irritability

Type 2 Diabetes
Any of the type 1 symptoms

Frequent infections

Blurred vision

Cuts or bruises that are slow to heal

Tingling or numbness in the hands or feet

Recurring skin, gum, or bladder infections

Note: People with type 2 diabetes often have no symptoms.

Source: American Diabetes Association.

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