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 per cent 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 per cent
of new diabetes cases in non-Hispanic white children ages 10 to 19, but
anywhere from 22 to 76 per cent 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.” 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 behavioural
and lifestyle factors. Data from the Nurses’ Health Study suggest that 90 per cent
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 per cent 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 had not yet crossed the line to diabetes. In the group
assigned to weight loss and exercise, there were 58 per cent 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 per cent 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 per cent. 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 per cent; it also increases the risk of heart disease
(15 per cent) and early death (13 per cent). 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
per cent 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 per cent.
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 fibre
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 glycaemic 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 glycaemic index and glycaemic 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 glycaemic index had a 21 per cent higher
risk of developing type 2 diabetes, compared to women whose diets had the
lowest glycaemic 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 per cent 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 per cent 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 per cent.
2. Skip the sugary
drinks, and choose water, coffee, or tea instead.
Like refined grains, sugary
beverages have a high glycaemic 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 per cent
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 per cent. 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 per cent 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 per cent. 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 per cent.
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 per cent. 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
unhealthy “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 per cent
more likely to develop diabetes than non-smokers, 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.
