Introduction
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.
In 2007, diabetes cost the U.S. an estimated $116 billion in excess
medical spending, and an additional $58 billion in reduced productivity. 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. Worldwide, the number of adults with diabetes will rise from 285 million in 2010 to 439 million in the year 2030.
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.
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.
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.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.
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.
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. 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.
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.
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.
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.
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.
More recently, The Black Women’s Health Study reported similar
diabetes-prevention benefits for brisk walking of more than 5 hours per
week.
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).
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.
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.
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.
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.
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. Similar findings were reported in the Black Women’s Health Study.
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.
2. Skip the sugary drinks, and choose water, coffee, or tea instead.
Like refined grains, sugary beverages have a high glycemic load, and
drinking more of this sugary stuff is associated with increased risk of
diabetes. In the Nurses’ Health Study II, women who drank one or more
sugar-sweetened beverages per day had an 83 percent higher risk of type 2
diabetes, compared to women who drank less than one sugar-sweetened
beverage per month.
Combining the Nurses’ Health Study results with those from seven
other studies found a similar link between sugary beverage consumption
and type 2 diabetes: For every additional 12-ounce serving of sugary
beverage that people drank each day, their risk of type 2 diabetes rose
25 percent.
Studies also suggest that fruit drinks— Kool Aid, fortified fruit
drinks, or juices—are not the healthy choice that food advertisements
often portray them to be: Women in the Black Women’s Health study who
drank two or more servings of fruit drinks a day had a 31 percent higher
risk of type 2 diabetes, compared to women who drank less than one
serving a month.
How do sugary drinks lead to this increased risk? Weight gain may
explain the link: In both the Nurses’ Health Study II and the Black
Women’s Health Study, women who increased their consumption of sugary
drinks gained more weight than women who cut back on sugary drinks.
Several studies show that children and adults who drink soda or other
sugar-sweetened beverages are more likely to gain weight than those who
don’t, and that switching from these to water or unsweetened beverages can reduce weight.
Even so, however, weight gain caused by sugary drinks may not
completely explain the increased diabetes risk. There is mounting
evidence that sugary drinks contribute to chronic inflammation, high
triglycerides, decreased “good” (HDL) cholesterol, and increased insulin
resistance, all of which are risk factors for diabetes.
What to drink in place of the sugary stuff? Water is an excellent
choice. Coffee and tea are also good calorie-free substitutes for
sugared beverages (as long as you don’t load them up with sugar and
cream). And there’s convincing evidence that coffee may help protect
against diabetes; emerging research suggests that tea may hold diabetes-prevention benefits as well, but more research is needed.
There’s been some controversy over whether artificially sweetened
beverages are beneficial for weight control and, by extension, diabetes
prevention.
Some studies have found that people who regularly drink diet beverages
have a higher risk of diabetes than people who rarely drink such
beverages,
but there could be another explanation for those findings: People often
start drinking diet beverages because they have a weight problem or
have a family history of diabetes; studies that don’t adequately account
for these other factors may make it wrongly appear as though the diet
soda led to the increased diabetes risk. A recent long-term analysis on
data from 40,000 men in the Health Professionals Follow-Up Study finds
that drinking one 12-ounce serving of diet soda a day does not appear to
increase diabetes risk. So in moderation, diet beverages can be a good sugary-drink alternative.
3. Choose good fats instead of bad fats.
The types of fats in your diet can also affect the development of
diabetes. Good fats, such as the polyunsaturated fats found in liquid
vegetable oils, nuts, and seeds can help ward off type 2 diabetes. Trans fats do just the opposite.
These bad fats are found in many margarines, packaged baked goods,
fried foods in most fast-food restaurants, and any product that lists
“partially hydrogenated vegetable oil” on the label. Eating
polyunsaturated fats from fish—also known as “long chain omega 3” or
“marine omega 3” fats—does not protect against diabetes, even though
there is much evidence that these marine omega 3 fats help prevent heart
disease. If you already have diabetes, eating fish can help protect you against a heart attack or dying from heart disease.
4. Limit red meat and avoid processed meat; choose nuts, whole grains, poultry, or fish instead.
The evidence is growing stronger that eating red meat (beef, pork,
lamb) and processed red meat (bacon, hot dogs, deli meats) increases the
risk of diabetes, even among people who consume only small amounts. The
latest support comes from a “meta analysis,” or statistical summary,
that combined findings from the long-running Nurses’ Health Study I and
II and the Health Professionals Follow-Up Study with those of six other
long-term studies. The researchers looked at data from roughly 440,000
people, about 28,000 of whom developed diabetes during the course of the
study.
They found that eating just one daily 3-ounce serving of red meat—say, a
steak that’s about the size of a deck of cards—increased the risk of
type 2 diabetes by 20 percent. Eating even smaller amounts of processed
red meat each day—just two slices of bacon, one hot dog, or the
like—increased diabetes risk by 51 percent.
The good news from this study: Swapping out red meat or processed red
meat for a healthier protein source, such as nuts, low-fat dairy,
poultry, or fish, or for whole grains lowered diabetes risk by up to 35
percent. Not surprisingly, the greatest reductions in risk came from
ditching processed red meat.
Why do red meat and processed red meat appear to boost diabetes risk?
It may be that the high iron content of red meat diminishes insulin’s
effectiveness or damages the cells that produce insulin; the high levels
of sodium and nitrites (preservatives) in processed red meats may also
be to blame. Red and processed meats are a hallmark of the unhealthful
“Western” dietary pattern, which seems to trigger diabetes in people who
are already at genetic risk
If You Smoke, Try to Quit
Add type 2 diabetes to the long list of health problems linked with
smoking. Smokers are roughly 50 percent more likely to develop diabetes
than nonsmokers, and heavy smokers have an even higher risk
Alcohol Now and Then May Help
A growing body of evidence links moderate alcohol consumption with
reduced risk of heart disease. The same may be true for type 2 diabetes.
Moderate amounts of alcohol—up to a drink a day for women, up to two
drinks a day for men—increases the efficiency of insulin at getting
glucose inside cells. And some studies indicate that moderate alcohol
consumption decreases the risk of type 2 diabetes.
If you already drink alcohol, the key is to keep your consumption in
the moderate range, as higher amounts of alcohol could increase diabetes
risk.
If you don’t drink alcohol, there’s no need to start—you can get the
same benefits by losing weight, exercising more, and changing your
eating patterns.
The Bottom Line: Preventing Type 2 Diabetes
They key to preventing type 2 diabetes can be boiled down to five words: Stay lean and stay active.
References: http://www.hsph.harvard.edu/nutritionsource/preventing-diabetes-full-story/
