Preventing diabetes: Understanding and diagnosing the
About 21 million Americans have diabetes, but a third of them don’t
know it. That means 7% of American adults are diabetic and many more
have impaired fasting glucose, which is better known as pre-diabetes.
These are worrisome figures, but the explosive increase in the disease
is more worrisome still. The prevalence of diabetes increased by about
40% during the 1990s and rose by another 8% in the year 2000. And every
projection indicates that it will continue to grow in the future.
Since the disease becomes more common as people age, it’s tempting
to ascribe the surge in diabetes to our aging population. That’s
part of the explanation — but only a small part. In fact, the greatest
increase in diabetes has occurred in children and adolescents.
Does it matter?
It sure does. Men with diabetes are about twice as likely to develop
heart disease as those without diabetes. In addition, diabetes is a major
cause of kidney failure, loss of vision, peripheral artery disease, leg
amputation, and cognitive impairment.
All in all, diabetes shortens life expectancy by about 13 years; no
wonder it’s the sixth leading cause of death in the United States,
taking about 300,000 lives annually.
What is diabetes?
To understand diabetes, you should first understand how your body handles
glucose, the sugar that fuels your metabolism. After you eat, your digestive
tract breaks down carbohydrates into simple sugars that are small enough
to be absorbed into your bloodstream. Glucose is the most important of
these sugars, and it’s an indispensable source of energy for your
body’s cells. But to provide that energy, it must travel from your
blood into your cells.
Insulin is the hormone that unlocks the door to your cells. When your
blood glucose levels rise after a meal, the beta cells of your pancreas
spring into action, pouring insulin into your blood. If you produce enough
insulin and your cells respond normally, your blood sugar level drops
as glucose enters the cells, where it is burned for energy or stored
in your liver as glycogen for future use. A mild elevation of blood sugar
doesn’t produce any symptoms. But even mild diabetes is dangerous,
since it damages blood vessels and other vital organs. When sugar levels
get higher, they produce symptoms that may include fatigue and blurred
vision. Excess sugar spills into the urine, taking water with it. This
produces excessive urination and dehydration, which lead to increased
thirst. Excess hunger is another symptom, and weight loss may develop
despite a hearty appetite. This happens because while the blood has too
much sugar, the cells don’t get enough.
The three types of diabetes
The name diabetes encompasses three different disorders that are all
marked by abnormally high blood sugar levels.
Type 1 diabetes was formerly known as juvenile or insulin-dependent
diabetes. It usually begins abruptly before the age of 20, often with
a critical rise in blood sugar levels. The disease is caused by a combination
of genetic abnormalities and environmental triggers that cause the body’s
immune system to attack the pancreas, destroying its ability to produce
insulin. Type 1 diabetes is the most severe form of the disease, but
it accounts for only about 5% of cases in the United States. Lifelong
insulin therapy is mandatory.
Type 2 diabetes was once called adult-onset or non-insulin-dependent
diabetes. In most cases, the main problem is insulin resistance. The
pancreas produces reasonable amounts of the hormone, but the body’s
tissues don’t respond properly, so blood sugar levels are abnormally
high. Oral medications can help many patients compensate for insulin
resistance. But over time, the ability of the overtaxed pancreas to secrete
insulin may run down, requiring insulin therapy.
Lifestyle factors are the major contributors to the disease, with obesity
heading the list.
Gestational diabetes, which occurs during pregnancy,
increases the risk of complications for mother and child. Blood sugar
levels return to normal after delivery, but many women develop type 2
diabetes later in life.
The American Diabetes Association (ADA) has proposed a simple standard
for the diagnosis of diabetes: a fasting blood sugar of 126 mg/dL or
higher, providing the result is confirmed on a second test. Fasting blood
sugars between 100 and 125 indicate impaired glucose tolerance, a milder
condition that may lead to diabetes; levels below 100 are officially
Although a fasting blood sugar of 126 is the standard for diagnosing
diabetes, two other criteria are also available. Any blood sugar level
above 200 suggests the diagnosis, even if it’s obtained after eating.
A third way to evaluate diabetes is to see what percent of the oxygen-carrying
hemoglobulin molecules in a person’s red blood cells have glucose
attached to them. When should you be tested for diabetes? It’s
most convenient when you’re having a regular checkup, especially
if you are already fasting for a cholesterol check. The ADA recommends
a test every three years for people 45 or older. Individuals with risk
factors such as being obese or overweight, having a diabetic parent or
sibling, or having high blood pressure or high cholesterol levels should
begin testing earlier and should have repeat tests as often as once a
year. Diagnosing diabetes early is important because prompt and aggressive
treatment can help ward off the often-deadly complications of the disease.
But preventing it from developing in the first place is even better.
July 2007 update
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