The gathering storm: the pre-diabetes epidemic.

Roughly one out of ten middle-aged Americans has diabetes. Among people 60 or older, it's nearly one out of five. But that's not what worries experts the most.

Add to those numbers another one in five who has what doctors call pre-diabetes and you've got a nation at risk. And not just for diabetes, but for heart attacks, strokes, kidney failure, blindness, nerve damage, and amputations.

The good news: diabetes isn't inevitable. People with pre-diabetes can cut their odds of getting the disease by nearly 60 percent. And we're talking healthy eating and exercise, not drugs.

The numbers are sobering.

An estimated 18 million Americans have diabetes. A third of them don't know it. And the numbers are expected to climb as the nation gets older, fatter, and more sedentary.

What's more, researchers now know that diabetes doesn't just appear out of nowhere.

"Another 41 million people in the country have pre-diabetes, and most of them don't know it, " says Judith Fradkin, director of the Diabetes, Endocrinology, and Metabolic Diseases Division of the National Institute of Diabetes & Digestive & Kidney Diseases in Bethesda, Maryland.

That's bad news, but it's also good news.

If people with pre-diabetes lose weight and exercise, they can turn back the clock. Says Fradkin: "We now have proof that we can delay or prevent this devastating disease."

A healthy diet plus exercise also makes a difference, even if you don't shed any pounds. "Our studies suggest that people who are overweight can reduce their risk of diabetes by 55 percent if they adopt a healthy lifestyle," says Walter Willett of Harvard University.

Blood Sugar Blues

If your blood sugar is higher than normal but not high enough to be called diabetes, you have pre-diabetes.

"We used to call it impaired fasting glucose or impaired glucose tolerance, but that was quite a mouthful," explains Judith Fradkin of the National Institute of Diabetes & Digestive & Kidney Diseases. "We wanted a user-friendly term that would roll off the tongue more easily."

More importantly, she adds, "we wanted to get across that people with pre-diabetes not only have a high risk of diabetes, but that pre-diabetes is also a risk factor for cardiovascular disease in its own right."

Your risk of a heart attack or stroke is two to four times higher if you have diabetes than if you don't. It's 1 1/2 times higher if you have pre-diabetes, says Fradkin.

"And between a third and half will go on to develop diabetes within five or ten years," says Frank Vinicor, director of the Diabetes Program at the Centers for Disease Control and Prevention in Atlanta.

But they don't have to.

Better Than Drugs

The proof is in the DPP.

Two years ago, researchers released the results of the Diabetes Prevention Program, in which they randomly assigned more than 3,000 overweight adults with pre-diabetes to one of three groups.

The placebo group was advised to lose weight and exercise. Ditto for people in the drug group, who were also given the prescription drug Glucophage to lower their blood sugar. The lifestyle group got intensive counseling (at first weekly, and then monthly) nudging them to exercise for 2 1/2 hours a week and to eat less. (1)

"We told them to cut their fat intake as a means of losing weight," says Rena Wing, one of the study's investigators who is now at Brown University Medical School in Providence, Rhode Island.

The results were so impressive that the researchers stopped the trial a year early.

"Diet and exercise lowered the risk of diabetes by 58 percent," says Wing. "That's dramatic."

Glucophage cut the risk by 31 percent, but it didn't work as well in people who were overweight but not obese or in people who were over 60. In contrast, "lifestyle changes worked across the board--at any weight and in both genders, all ethnic groups, and all age groups," says Wing.

"If anything, the older people responded particularly well and had some of the greatest reductions in risk."

It's not just that lifestyle works, she adds. It's that small changes work.

"The results were powerful because they showed that a modest amount of weight loss and physical activity was enough," says Wing. People lost an average of 14 pounds and exercised for a little over 3 1/2 hours a week.

"If I told people that they had to lose 50 pounds, they'd say 'no way,'" explains Wing. "But if I said that they'd only have to lose 14 pounds and exercise for 30 minutes a day--10 minutes in the morning, 10 at lunch, and so on--that's within everyone's reach."

Since then, similar studies have confirmed the DPP's findings. (2) "A study in Finland found the identical reduction in risk--S8 percent," says Fradkin. "That's a huge effect."

"We want people with pre-diabetes to know that they don't need to reach their ideal body weight," she adds. "Losing ten pounds makes a big difference."

How to get there? Most experts agree that cutting back on unhealthy fats and carbs is a good start (see "Losing It').

Don't Weight

It should come as no surprise that weight loss is key. Four out of five people with "type 2" diabetes (what doctors used to call "adult-onset") are overweight.

In "type 1" diabetes (which used to be called "juvenile onset"), the body's immune system destroys its own insulin-producing cells. Without insulin, blood sugar can't enter the cells, where it's burned for energy.

In people with type 2 diabetes, the cells become resistant to the hormone. So the insulin shows up, but it doesn't do its job efficiently. Scientists are beginning to figure out why.

"Fat cells used to be thought of as passive storehouses for fat," explains Vinicor. "Now we think of them as active endocrine organs that produce hormones." For example, after a meal, fat cells release leptin, which signals the brain to stop eating.

"But fat cells respond if they're abused," says Vinicor. Eat too much and your overstuffed fat cells produce hormones that cause insulin resistance. Why?

"If a fat or muscle cell becomes resistant to insulin, sugar won't be driven into it and stored as fat," he says. "It's a self-protective mechanism."

Insulin resistance may keep the cells from bursting at the seams, but it isn't harmless.

"The consequences of insulin resistance aren't so healthy," says Vinicor. "It may cause high blood pressure, high triglycerides, and inflammation in the blood vessels." That may explain why people who are insulin resistant have a higher risk of heart attack and stroke.

Without insulin doing its job, blood sugar levels start to climb, prompting the beta-cells in the pancreas to secrete more insulin to keep up. "Gradually the beta-cells peter out," explains Vinicor. "That's when blood sugar levels rise into the diabetic range."

But that doesn't have to happen. "If you can lose a little weight and exercise, it can take the pressure off the beta-cells," says Vinicor. "We don't know if that can prevent diabetes, but we know that it can delay it."

Beyond Weight Loss

If you want to keep diabetes at bay, weight loss is a slam dunk. But the evidence is also mounting that it's not just how much, but what you eat that can raise or lower your risk (see "What Else May Work").

"The strongest risk factor is weight," says Walter Willett, chair of the nutrition department at Harvard Medical School. "But we've also calculated that even without weight loss, the overweight can reduce their risk by 55 percent--and the obese by 30 percent--if they eat a healthy diet, stay moderately active, and don't smoke."

Adding a healthy weight to the equation cuts the risk further. "Among women who adopted this healthy lifestyle and were not overweight, the risk of diabetes was 90 percent lower," he explains.

In Willett's calculations, a healthy lifestyle means: (3)

* No current smoking. Smokers have a higher risk.

* Exercise. Half an hour a day of brisk walking or similar aerobic activity lowers the risk.

* Good fats. More polyunsaturated fat (in vegetable oils, nuts, salad dressings, mayonnaise, etc.) and less saturated fat (in red meats, cheese, butter, etc.)and especially less trans fat (from partially hydrogenated oils in margarine, shortening, etc.)--seem to lower the risk.

* Good carbs. Risk is lower in people who consume more whole grains--probably because the grains are rich in fiber and magnesium--and fewer refined starches and sugars.

That's consistent with other evidence, Willett adds. "High intakes of highly refined starches and sugars make blood sugar control worse once you have diabetes."

* Alcohol. Women who average as little as half a serving of alcoholic beverages a day have a lower risk than nondrinkers. Men who have one or two drinks every day have a lower risk than men who drink less often.

"Alcohol seems to reduce insulin resistance, but people shouldn't start drinking to reduce their risk of diabetes," cautions Willett, Heavy drinking may raise diabetes risk. And even light drinking increases the risk of breast cancer.

Willett's calculations aren't as definitive as studies (like the DPP) that actually put people on a diet and watch to see who gets diabetes. But they're compelling nonetheless. And since those calculations were done, studies have uncovered other foods that affect risk (see "What Else May Work," p. 5).

For example, people who regularly drink coffee (with caffeine) have a lower risk, while those who eat more bacon, hot dogs, sausage, and other processed meats have a higher risk. "We don't know why," says Willett.

In contrast, the reason nut eaters have a lower risk is less mysterious. "Nuts are a good source of magnesium and polyunsaturated fats, and they may displace unhealthy fats," says Willett.

Even without proof that Willett's "healthy lifestyle" can prevent diabetes, there's reason enough to adopt it: a lower risk of heart disease. And diabetes is a greater threat to the heart than most people realize.

Heart & Whole

Once the body loses its ability to control blood sugar levels, the harm spreads from your eyes to your feet (see "From Head to Toe"). "Diabetes affects the total body because blood sugar goes everywhere in the body," says the CDC's Frank Vinicor.

For decades, experts have worried that too much sugar damages small blood vessels, leading to blindness, kidney failure, and amputations. But now the spotlight is shifting.

"Small-vessel problems that affect the kidney, eyes, and nervous system are devastating," says Vinicor. "But large-vessel problems like heart attacks and strokes are far and away the most common lethal complications of diabetes. Sixty percent of diabetics die of a heart attack and 20 percent die of a stroke."

The numbers are discouraging: Over the last 30 years, heart disease death rates have dropped by 27 percent among U.S. women. But in women with diabetes, rates jumped by 23 percent. Over the same period, heart disease fell by 36 percent in U.S. men, but only by 13 percent for men with diabetes.

"Heart disease rates have gone down, but not necessarily for people with diabetes," says Fradkin.

In a recent study she co-authored, only five to seven percent of more than 1,500 people with diabetes had blood pressure, cholesterol, and blood sugar at recommended levels---even though some were taking medications. (4)

The National Diabetes Education Program has launched a campaign to reach doctors and patients (see "Know Your ABCs").

"Patients need to understand that if they have diabetes, their risk of having a heart attack is as high as the risk of someone without diabetes who's already had a heart attack," explains Fradkin.

Get Tested

Getting diabetes on the public's radar screen is the first step. "People need to think about diabetes because most times, the disease shows no symptoms unless you have very high blood sugar or complications," says Fradkin.

"Everyone 45 or older should get their blood sugar tested at least every three years if the results are good the first time around," says Vinicor. That's true even if you're not overweight. "Those people don't arouse suspicion but they can still be insulin resistant" (see "What's Your Risk?").

Doctors can measure blood sugar at least 12 hours after eating (fasting blood glucose) or two hours after the patient drinks a glucose-laden liquid (glucose tolerance).

"In older people, the fasting test is less likely to pick up problems than the two-hour test," says Fradkin. "But many doctors start with a fasting glucose and, if the numbers are in the upper range, they do a glucose tolerance test."

Measuring hemoglobin A1C isn't good for diagnosing diabetes. "A1C isn't reliable in pre-diabetes or in the early stages of the disease," says Fradkin. "It measures how much sugar has attached to the hemoglobin in blood cells over the last three months, so it's a measure of long-term control."

But once a patient has diabetes, doctors should measure hemoglobin A1C (see "Know Your ABCs"). "It's only recently that doctors could do the test in the office," explains Fradkin. "Sending the test off used to build in a delay but now they're able to get instant results."

While doctors may measure A1C, they may not do enough to knock it down to recommended levels, she adds. "That's why we want patients to ask questions like 'What is my A1C? What should it be? And how do we get it there?'"

Ditto for blood cholesterol and blood pressure. Even if a patient already has suffered some damage to their eyes, kidneys, or nerves, it's not too late.

"At every stage of diabetes, we have proven effective therapies," says Fradkin. "If you have pre-diabetes, you can prevent or delay it from becoming diabetes, if you have diabetes, you can prevent or delay complications, and if you have complications, you can slow their progression to blindness and other end-stage complications. Being aggressive makes a difference."

Do You Have Pre-Diabetes?

People with pre-diabetes have blood sugar levels that are higher than normal but not high enough to be diabetic. The cutoffs depend on whether your blood is tested after a 12-hour fast (fasting blood sugar) or two hours after you're given a glucose-laden liquid to drink (oral glucose tolerance test.)

Source: American Diabetes Association (www.diabetes.org/pre-diabetes/pre-diabetes-symptoms.jsp).

Losing It

What's the quickest route to a slimmer you?

Researchers are still awaiting a handful of longer-term studies that pit an Atkins-type diet (low-carb, high-fat) against a typical lower-calorie diet. Meanwhile, the lines in the diet wars are blurring.

Atkins, for example, used to push a diet loaded with red meat, cheese, cream, bacon, and eggs. Now the Atkins Web site favors healthy fats.

"In all phases of Atkins, it is a good idea to get much of your fat from fatty fish such as salmon, tuna and sardines, nuts and seeds and olive oil which has well-documented health benefits," the site explains in answer to a question.

The popular South Beach Diet offers a clearer message: dodge unhealthy fats and avoid "bad" carbs (by minimizing sweets and switching from refined to whole grains).

Avoiding bad fats and bad carbs makes even more sense if you're at risk for diabetes. Bad fats (saturated and trans) can boost the risk of heart disease, the leading cause of death in people with diabetes. And people who eat whole grains have a lower risk of diabetes than those who load up on low-fiber, refined grains and sweets. The bottom line:

* Less bad. Cut back on calories from bad fats and bad carbs. (That includes french fries, burgers, pizza, movie-theater popcorn, nachos, sweets, etc.)

* More good. Build your diet around vegetables, seafood, poultry, low-fat dairy foods, beans, and whole grains, plus some oils, nuts, and other unsaturated fats.

* Eat half out. With most restaurant meals in the 1,000-calorie range, think about ordering one entree for every two people (or taking half home).

What Else May Work

Losing excess weight and boosting your physical activity are far and away the best ways to avoid diabetes. But preliminary studies have also identified foods that are linked to a lower (or higher) risk.

It's still not clear whether its the foods--or something else about the people who eat them--that matters. But it wouldn't hurt to eat (or avoid) them if that doesn't cause other problems. For example, eating more fiber is good for your heart and your gut, even if it doesn't reduce your risk of diabetes. On the other hand, drinking four or five cups of regular coffee a day may give people insomnia and the jitters. And alcohol--even one drink a day--can raise the risk of breast cancer and, in some people, lead to alcohol abuse.

                      People                Who typically

Alcohol (1,2)         Women                 had 1/2 drink
                                            a day
                      Men                   had 1-2 drinks
                                            a day

Coffee (3)            Women                 drank 4-5 cups
                      or                    of regular coffee
                      Men                   a day

Fiber (4,5)           Women                 ate 8-10 grams a
                      or                    day of fiber from
                      Men                   breads, cereals,
                                            and other grains

Magnesium (6)         Women                 ate 375 mg a day
                      Men                   ate 450 mg a day

Nuts (7)              Women                 ate nuts at least
                                            five times a week

Polyunsaturated       Women                 ate 14 grams a
fats (8)                                    day of polyun-
                                            saturated fats
                                            (for a 2,000-
                                            calorie diet)

Whole grains (9,10)   Women                 ate 3 servings a
                      or                    day of whole
                      Men                   grains

Processed             Women                 ate bacon, hot
meats (11,12)         or                    dogs, or sausage
                      Men                   at least 5 times a
                                            week

Trans fats (8)        Women                 ate 6 grams a
                                            day of trans fat

                      Had roughly a         Than those
                                            who typically

Alcohol (1,2)         40% lower risk        never drank

                      40% lower risk        had 1-2 drinks a
                                            week or less

Coffee (3)            30% lower risk        almost never
                                            drank coffee

Fiber (4,5)           30% lower risk        ate 2-3 grams a
                                            day of fiber from
                                            breads, cereals,
                                            and other grains

Magnesium (6)         25% lower risk        ate 220 mg a day
                      30% lower risk        ate 270 mg a day

Nuts (7)              30% lower risk        almost never ate
                                            nuts

Polyunsaturated       25% lower risk        ate 6 grams a
fats (8)                                    day of polyun-
                                            saturated fats
                                            (for a 2,000-
                                            calorie diet)

Whole grains (9,10)   30% lower risk        ate 1 serving
                                            every 3-8 days of
                                            whole grains

Processed             90% higher            ate bacon, hot
meats (11,12)         risk (women)          dogs, or sausage
                                            less than once a
                      45% higher            week (women)
                      risk (men)            or once a month
                                            (men)

Trans fats (8)        30% higher            ate 3 grams a
                      risk                  day of trans fat

(1) N. Eng. J. Med. 345: 790, 2001.

(2) Diabetes 50: 2390, 2001.

(3) Ann. Intern. Med. 140: 1, 2004.

(4) J. Amer. Med. Assoc. 277: 472, 1997.

(5) Diabetes Care 20: 545, 1997.

(6) Diabetes Care 27: 134, 2004.

(7) J. Amer. Med. Assoc. 288: 2554, 2002.

(8) Amer. J. Clin. Nutr. 73: 1019, 2001.

(9) Amer. J. Public Health 90: 1409, 2000.

(10) Amer. J. Clin. Nutr. 76: 535, 2002.

(11) Diabetologia 46: 1465, 2003.

(12) Diabetes Care 25: 417, 2002.

What's Your Risk?

Most people with pre-diabetes don't know they have it. The only way to find out is to get your blood sugar tested (at least every three years starting at age 45). Your risk is higher if you:

* are age 45 or older

* are overweight (see table)

* are African American, Hispanic/Latino American, Asian American, Pacific Islander, or American Indian 

* have a parent, brother, or sister with diabetes

* have high blood pressure (above 140/90)

* have low HDL ("good") cholesterol (less than 40 for men; less than 50 for women)

* have high triglycerides (250 or higher)

* have had diabetes when pregnant or gave birth to a large baby (over 9 pounds)

* are active fewer than three times a week

You're overweight if you're

  Height           Weight
(no shoes)      (no clothes)

   4'10"            119
   4'11"            124
   5'0"             128
   5'1"             132
   5'2"             136
   5'3"             141
   5'4"             145
   5'5"             150
   5'6"             155
   5'7"             159
   5'8"             164
   5'9"             169
   5'10"            174
   5'11"            179
   6'0"             184
   6'1"             189
   6'2"             194
   6'3"             200
   6'4"             205

Source: Adapted from the National Diabetes Education Program (www.diabetes.org/risk-test/text-version.jsp).

Know Your ABCs

If you already have diabetes, ask your doctor to test your ABCs. "A" stands for the hemoglobin A1C test, which reflects average blood sugar over the previous three months. "B" stands for blood pressure. And "C" stands for for LDL ("bad") cholesterol. Then use diet and, if necessary, drugs to reach these targets.

Know Your ABCs

TEST                    TARGET          HOW OFTEN?

A1C (glucose average)   Below 7% *      At least twice a year

Blood Pressure          Below 130/80    At every doctors visit

Cholesterol (LDL)       Below 100       At least once a year

* An A1C of 7% equals an average blood glucose level of 150.

Source: National Institute of Diabetes & Digestive & Kidney Diseases
(www.niddk.nih.gov/welcome/releases/11-01-01.htm).

From Head to Toe

Diabetes strikes nearly every part of the body. But studies show that treating diabetes aggressively can curb the damage.

EYES

Diabetes is the leading cause of blindness among adults aged 20 to 74.

Every 1% reduction in A1C (from 8% to 7%, for example) lowers the risk of eye, kidney, and nerve disease by 40%.

Treating eye disease with laser therapy can reduce severe vision loss by 50% to 60%.

KIDNEYS

Diabetes is the leading cause of end-stage kidney disease.

Detecting early diabetic kidney disease (by testing urine for protein each year) and treating it can curb the loss of kidney function by 30% to 70%.

NERVES

An estimated six out of ten people with diabetes have nerve damage that can cause problems like numbness or pain in the feet or hands, carps syndrome (in the wrist), and delayed digestion of food.

Lowering high blood pressure can reduce the risk of nerve, eye, and kidney damage by 33%.

BRAIN

People with diabetes are more likely to be diagnosed with dementia. Researchers don't know if the dementia is due to diabetes or to multiple mini-strokes (common in people with diabetes) that gradually impair mental function over time. If it's mini-strokes, lowering blood pressure might protect the brain.

HEART & BRAIN

The risk of heart attack or stroke is two to four times higher in people with diabetes.

Lowering high cholesterol can reduce heart attack and stroke by 20% to 50%.

Lowering high blood pressure can reduce the risk of heart attack and stroke by 33% to 50%.

FEET

Diabetes causes more than 60% of foot and leg amputations that are not caused by accidents.

Proper foot care (trim nails, check feet daily for red spots, cuts, swelling, blisters, etc.) can reduce the risk of amputation by 45% to 85%.

Source: www.cdc.gov/diabetes/pubs/pdf/ndfs_2003.pdf.

(1) N. Eng. J. Med. 346: 393, 2002.

(2) J. Amer. Soc. Nephrol. 14: S108, 2003.

(3) New Eng. J. Med. 345: 790, 2001.

(4) J. Amer. Med. Assoc. 291: 335, 2004.