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Diabetes Overview
Diabetes Overview
What is diabetes?
Diabetes mellitus is a disease that prevents your body from properly using the energy from the food you
eat. Diabetes can occur when the pancreas (an organ behind your stomach) produces little insulin or no
insulin at all. It also can occur when the pancreas makes insulin, but the insulin made does not work as it
should. This condition is called insulin resistance.
What is insulin?
Insulin is a naturally-occurring hormone-- produced by the beta cells of the pancreas-- that helps the body
use glucose for energy.
Understanding metabolism
To understand diabetes better, it helps to know more about how the body uses food for energy (a process
called metabolism). Your body is made up of millions of cells. To make energy, the cells need food in a
very simple form. When you eat or drink, much of your food is broken down into a simple sugar called
glucose. Glucose (sugar) provides the energy your body needs for daily activities.
The blood and blood vessels are the highways that transport glucose from where it is either taken in (the
stomach) or manufactured (in the liver) to the cells where it is used (muscles) or where it is stored (fat).
Glucose cannot go into the cells by itself. The pancreas releases a substance called insulin into the blood
which serves as the helper, or the "key" that lets glucose into the cells for use as energy. When glucose
leaves the bloodstream and enters the cells, the blood glucose level is lowered.
Compare the human body to a car. To start a car, you must turn the key to move the gas to the engine.
Without insulin, or the "key," glucose cannot get into the body's cells for use as energy. This causes
glucose to rise. Too much glucose in the blood is called "high blood sugar" or diabetes.
Types of diabetes
Type 1 diabetes
Type 1 diabetes occurs because the insulin-producing cells (called beta cells) of the pancreas are damaged.
People with type 1 diabetes produce little or no insulin, so glucose cannot get into the body's cells for use
as energy. This causes blood glucose to rise. People with type 1 diabetes MUST use insulin injections to
control their blood glucose.
The damage to insulin-producing cells in type 1 diabetes occurs over a period of years. However, the
symptoms of type 1 diabetes may occur over a period of days to weeks. Type 1 is the most common form
of diabetes in people under age 20, but it can occur at any age.
Type 2 diabetes
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Diabetes Overview
Unlike people with type 1 diabetes, people with type 2 diabetes produce insulin. However, the insulin
produced is either not enough or doesn't work properly in the body. When there is not enough insulin or
the insulin is not used as it should be, glucose cannot get into the body's cells for use as energy. This
causes blood glucose to rise.
Type 2 diabetes is most common in people who are over age 40 and who are overweight. Some people
with type 2 diabetes can manage it by controlling their weight, watching their diet, and exercising
regularly. Others may also need to take an oral glucose-lowering medication or insulin injections.
Gestational diabetes
Gestational diabetes is a high blood glucose level that occurs during pregnancy. As pregnancy progresses,
the developing baby has an increased need for glucose. Hormone changes during pregnancy also affect the
action of insulin, resulting in high blood glucose levels.
Pregnant women who have an increased risk of developing gestational diabetes include those who:
are over 25 years old
are above their normal body weight
have a family history of diabetes, and
are Hispanic, African-American, Native American, or Asian.
Usually, blood glucose levels return to normal after childbirth. However, women who have had gestational
diabetes have an increased risk of developing type 2 diabetes later in life.
What are the symptoms of diabetes?
The symptoms of type 1 diabetes are often sudden and severe. These symptoms include:
Increased thirst
Increased hunger (especially after eating)
Dry mouth
Frequent urination
Unexplained weight loss (even though you are eating and feel hungry)
Fatigue (weak, tired feeling)
Blurred vision
Numbness or tingling of the hands or feet
Loss of consciousness (rare)
The symptoms of type 2 diabetes may be the same as those listed above. Most often, there are no
symptoms or a very gradual development of the symptoms of type 1 diabetes.
Other symptoms include:
Slow healing sores or cuts
Itching of the skin (usually in the vaginal or groin area)
Yeast infections
Diabetes risk factors
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Diabetes Overview
Although the causes of diabetes are unknown, the following risk factors may increase your chance of
developing diabetes:
A family history of diabetes (if a parent or sibling in your family has diabetes)
Race or ethnic background (the risk of diabetes is greater in Hispanics, African-Americans, Native
Americans, and Asians)
Being overweight (20 percent or more over your desired body weight)
Hypertension (high blood pressure)
Abnormal blood cholesterol or triglyceride levels: HDL or "good" cholesterol level under 45 mg/dl
for men and 55 mg/dl for women, and/or a triglyceride level over 150 mg/dl.
Age: Your risk of developing diabetes rises progressively as you get older.
Use of certain drugs:
Blood pressure medications (such as thiazides)
Steroid medications (such as prednisone or Decadron [dexamethasone])
Hydantoin medications (such as Dilantin [phenytoin])
Medications for transplant recipients (such as cyclosporine)
Alcohol, especially if you have been a heavy drinker for years
Smoking
History of gestational diabetes (developing diabetes during pregnancy) or delivery of babies who
weigh more than 9 pounds
Autoimmune disease: Your body's defense system (immune system) attacks certain healthy cells in
your pancreas that produce insulin (beta cells).
Other factors, such as viruses, which may play a part in diabetes development
It is important to note that sugar itself does not cause diabetes. Eating a lot of sugar can lead to tooth
decay, but it does not cause diabetes.
How is diabetes diagnosed?
If you suddenly experience symptoms of increased thirst, frequent urination, or unexplained weight loss,
diabetes may be the cause. To confirm the diagnosis, a fasting plasma glucose (FPG) test, a casual plasma
glucose test, or an A1c test (glycated hemoglobin) will be performed.
The FPG measures your blood glucose level after you have fasted (not had anything to eat or drink) for at
least 8 hours. Normal fasting blood glucose is between 70 and 100 mg/dl for people who do not have
diabetes. The standard diagnosis of diabetes is made when two blood tests on different days show that your
fasting blood glucose level is greater than or equal to 126 mg/dl. If the results are between 100 and 125
mg/dl, you are at risk.
Some people have a normal fasting blood glucose reading, but their blood glucose rises rapidly as they eat.
These people may have glucose intolerance. If their blood glucose levels are between 100 and 125 mg/dl,*
they may be considered to have diabetes.
In a casual plasma glucose test, blood glucose is tested without regard to the time since the person's last
meal. A glucose level greater than 200 mg/dl may indicate diabetes, especially if the test is repeated at a
later time and indicates similar results.
The oral glucose tolerance test is another method used to detect diabetes, but is not routinely performed
except during pregnancy.
How is diabetes managed?
There is no cure for diabetes, but it can be treated and controlled. The goals of managing diabetes are to:
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Diabetes Overview
1. Keep your blood glucose levels as near to normal as possible by balancing food intake, activity, and
taking with medication and activity.
2. Maintain your blood cholesterol and triglyceride (lipid) levels as near the normal ranges as possible
by decreasing the total amount of fat to 30% or less of your total daily calories and by reducing
saturated fat and cholesterol.
3. Control your blood pressure. (Your blood pressure should not go over 130/80.)
4. Decrease or possibly prevent the development of diabetes-related health problems.
You hold the keys to managing your diabetes by:
Planning what you eat and following a balanced meal plan
Exercising regularly
Taking medication, if prescribed, and closely following the guidelines on how and when to take it
Monitoring your blood glucose and blood pressure levels at home
Keeping your appointments with your health care providers and having laboratory tests completed as
ordered by your doctor.
What you do at home every day affects your blood glucose more than what your doctor can do every few
months during your check-ups.
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health
care provider. Please consult your health care provider for advice about a specific medical condition. For additional health
information, please contact the Center for Consumer Health Information at the Cleveland Clinic (216) 444-3771 or toll-free (800)
223-2273 extension 43771. If you prefer, you may visit www.clevelandclinic.org/health/ or www.clevelandclinicflorida.org. This
document was last reviewed on: 10/12/2010
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