If type 2 diabetes was an infectious disease, passed from one person to another, public health officials would say we’re in the midst of an epidemic. This difficult disease, once called adult-onset diabetes, is striking an ever-growing number of adults. Even more alarming, it’s now beginning to show up in teenagers and children.
More than 24 million Americans have diabetes; of those, about 6 million don’t know they have the disease. (1) In 2007, diabetes cost the U.S. an estimated $116 billion in excess medical spending, and an additional $58 billion in reduced productivity. (1) If the spread of type 2 diabetes continues at its present rate, the number of people diagnosed with diabetes in the United States will increase from about 16 million in 2005 to 48 million in 2050. (2) Worldwide, the number of adults with diabetes will rise from 285 million in 2010 to 439 million in the year 2030. (3)
The problems behind the numbers are even more alarming. Diabetes is the leading cause of blindness and kidney failure among adults. It causes mild to severe nerve damage that, coupled with diabetes-related circulation problems, often leads to the loss of a leg or foot. Diabetes significantly increases the risk of heart disease. And it’s the seventh leading cause of death in the U.S., directly causing almost 70,000 deaths each year and contributing to thousands more. (4)
The good news is that type 2 diabetes is largely preventable. About 9 cases in 10 could be avoided by taking several simple steps: keeping weight under control, exercising more, eating a healthy diet, and not smoking.
What Is Type 2 Diabetes?
Our cells depend on a single simple sugar, glucose, for most of their energy needs. That’s why the body has intricate mechanisms in place to make sure glucose levels in the bloodstream don’t go too low or soar too high.
When you eat, most digestible carbohydrates are converted into glucose and rapidly absorbed into the bloodstream. Any rise in blood sugar signals the pancreas to make and release insulin. This hormone instructs cells to sponge up glucose. Without it, glucose floats around the bloodstream, unable to slip inside the cells that need it.
Diabetes occurs when the body can’t make enough insulin or can’t properly use the insulin it makes.
One form of diabetes occurs when the immune system attacks and permanently disables the insulin-making cells in the pancreas. This is type 1 diabetes, once called juvenile-onset, or insulin-dependent, diabetes. Roughly 5 to 10 percent of diagnosed diabetes cases are type 1 diabetes. (5)
The other form of diabetes tends to creep up on people, taking years to develop into full-blown diabetes. It begins when muscle and other cells stop responding to insulin’s open-up-for-glucose signal. The body responds by making more and more insulin, essentially trying to ram blood sugar into cells. Eventually, the insulin-making cells get exhausted and begin to fail. This is type 2 diabetes.
Type 2 diabetes used to be called adult-onset diabetes, since it was almost unheard of in children. But with the rising rates of childhood obesity, it has become more common in youth, especially among certain ethnic groups.
In the U.S., the SEARCH for Diabetes in Youth Study found that type 2 diabetes accounted for only 6 percent of new diabetes cases in non-Hispanic white children ages 10 to 19, but anywhere from 22 to 76 percent of new cases in other ethnic groups (6).The highest rates were found in Asia-Pacific Islander and Native American youth.
In addition to the millions of adults with diabetes, another 57 million adults have “pre-diabetes.” (7) This early warning sign is characterized by high blood sugar levels on a glucose tolerance test or a fasting glucose test. Whether pre-diabetes expands into full-blown type 2 diabetes is largely up to the individual. Making changes in weight, exercise, and diet can not only prevent pre-diabetes from becoming diabetes, but can also return blood glucose levels to the normal range.
Type 2 Diabetes Can Be Prevented
Although the genes you inherit may influence the development of type 2 diabetes, they take a back seat to behavioral and lifestyle factors. Data from the Nurses’ Health Study suggest that 90 percent of type 2 diabetes in women can be attributed to five such factors: excess weight, lack of exercise, a less-than-healthy diet, smoking, and abstaining from alcohol. (8)
Among 85,000 married female nurses, 3,300 developed type 2 diabetes over a 16-year period. Women in the low-risk group were 90 percent less likely to have developed diabetes than the rest of the women. Low-risk meant a healthy weight (body mass index less than 25), a healthy diet, 30 minutes or more of exercise daily, no smoking, and having about three alcoholic drinks per week.
Similar factors are at work in men. Data from the Health Professionals Follow-up Study indicate that a “Western” diet, combined with lack of physical activity and excess weight, dramatically increases the risk of type 2 diabetes in men. (9)
Information from several clinical trials strongly supports the idea that type 2 diabetes is preventable. The Diabetes Prevention Program examined the effect of weight loss and increased exercise on the development of type 2 diabetes among men and women with high blood sugar readings that hadn’t yet crossed the line to diabetes. In the group assigned to weight loss and exercise, there were 58 percent fewer cases of diabetes after almost three years than in the group assigned to usual care. (10) Even after the program to promote lifestyle changes ended, the benefits persisted: The risk of diabetes was reduced, albeit to a lesser degree, over 10 years. (11) Similar results were seen in a Finnish study of weight loss, exercise, and dietary change, and in a Chinese study of exercise and dietary change. (12–15)
Simple Steps to Lower Your Risk
Making a few lifestyle changes can dramatically lower the chances of developing type 2 diabetes. The same changes can also lower the chances of developing heart disease and some cancers.
Control Your Weight
Excess weight is the single most important cause of type 2 diabetes. Being overweight increases the chances of developing type 2 diabetes seven fold. Being obese makes you 20 to 40 times more likely to develop diabetes than someone with a healthy weight. (8)
Losing weight can help if your weight is above the healthy-weight range. Losing 7 to 10 percent of your current weight can cut your chances of developing type 2 diabetes in half.
Get Moving—and Turn Off the Television
Inactivity promotes type 2 diabetes. (16) Working your muscles more often and making them work harder improves their ability to use insulin and absorb glucose. This puts less stress on your insulin-making cells.
Long bouts of hot, sweaty exercise aren’t necessary to reap this benefit. Findings from the Nurses’ Health Study and Health Professionals Follow-up Study suggest that walking briskly for a half hour every day reduces the risk of developing type 2 diabetes by 30 percent. (18, 19) More recently, The Black Women’s Health Study reported similar diabetes-prevention benefits for brisk walking of more than 5 hours per week. (20) This amount of exercise has a variety of other benefits as well. And even greater cardiovascular and other advantages can be attained by more, and more intense, exercise.
Television-watching appears to be an especially-detrimental form of inactivity: Every two hours you spend watching TV instead of pursuing something more active increases the chances of developing diabetes by 20 percent; it also increases the risk of heart disease (15 percent) and early death (13 percent). (17) The more television people watch, the more likely they are to be overweight or obese, and this seems to explain part of the TV viewing-diabetes link. The unhealthy diet patterns associated with TV watching may also explain some of this relationship.
Tune Up Your Diet
Four dietary changes can have a big impact on the risk of type 2 diabetes.
1. Choose whole grains and whole grain products over highly processed carbohydrates.
There is convincing evidence that diets rich in whole grains protect against diabetes, whereas diets rich in refined carbohydrates lead to increased risk (53). In the Nurses’ Health Studies I and II, for example, researchers looked at the whole grain consumption of more than 160,000 women whose health and dietary habits were followed for up to 18 years. Women who averaged two to three servings of whole grains a day were 30 percent less likely to have developed type 2 diabetes than those who rarely ate whole grains. (21) When the researchers combined these results with those of several other large studies, they found that eating an extra 2 servings of whole grains a day decreased the risk of type 2 diabetes by 21 percent.
Whole grains don’t contain a magical nutrient that fights diabetes and improves health. It’s the entire package—elements intact and working together—that’s important. The bran and fiber in whole grains make it more difficult for digestive enzymes to break down the starches into glucose. This leads to lower, slower increases in blood sugar and insulin, and a lower glycemic index. As a result, they stress the body’s insulin-making machinery less, and so may help prevent type 2 diabetes. (22) Whole grains are also rich in essential vitamins, minerals, and phytochemicals that may help reduce the risk of diabetes.
In contrast, white bread, white rice, mashed potatoes, donuts, bagels, and many breakfast cereals have what’s called a high glycemic index and glycemic load. That means they cause sustained spikes in blood sugar and insulin levels, which in turn may lead to increased diabetes risk. (22) In China, for example, where white rice is a staple, the Shanghai Women’s Health Study found that women whose diets had the highest glycemic index had a 21 percent higher risk of developing type 2 diabetes, compared to women whose diets had the lowest glycemic index. (23) Similar findings were reported in the Black Women’s Health Study. (24)
More recent findings from the Nurses Health Studies I and II and the Health Professionals Follow-Up Study suggest that swapping whole grains for white rice could help lower diabetes risk: Researchers found that women and men who ate the most white rice—five or more servings a week—had a 17 percent higher risk of diabetes than those who ate white rice less than one time a month. People who ate the most brown rice—two or more servings a week—had an 11 percent lower risk of diabetes than those who rarely ate brown rice. Researchers estimate that swapping whole grains in place of even some white rice could lower diabetes risk by 36 percent. (25)