does insulin do?
How are insulin resistance, pre-diabetes,
and type 2 diabetes linked?
What causes insulin resistance?
What are the symptoms of insulin resistance and pre-diabetes?
Do you have insulin resistance or pre-diabetes?
you reverse insulin resistance?
Be Active and Eat Well
Can medicines help?
resistance is a silent condition that increases the chances of developing diabetes
and heart disease. Learning about insulin resistance is the first step you can
take toward making lifestyle changes that will help you prevent diabetes and other
does insulin do?
After you eat, the food is broken down into glucose,
the simple sugar that is the main source of energy for the body's cells. But your
cells cannot use glucose without insulin, a hormone produced by the pancreas.
Insulin helps the cells take in glucose and convert it to energy. When the pancreas
does not make enough insulin or the body is unable to use the insulin that is
present, the cells cannot use glucose. Excess glucose builds up in the bloodstream,
setting the stage for diabetes.
obese or overweight affects the way insulin works in your body. Extra fat tissue
can make your body resistant to the action of insulin, but exercise helps insulin
are insulin resistance, pre-diabetes, and type 2 diabetes linked?
If you have insulin resistance, your muscle, fat, and liver cells do not use insulin properly. The
pancreas tries to keep up with the demand for insulin by producing more. Eventually, the pancreas
cannot keep up with the body’s need for insulin, and excess glucose builds up in the bloodstream.
Many people with insulin resistance have high levels of blood glucose and high levels of insulin
circulating in their blood at the same time.
People with blood glucose levels that are higher than normal but not yet in the diabetic range have
“pre-diabetes.” Doctors sometimes call this condition impaired fasting glucose (IFG) or impaired
glucose tolerance (IGT), depending on the test used to diagnose it. Pre-diabetes is becoming more
common in the United States, according to new estimates provided by the U.S. Department of Health
and Human Services. About 40 percent of U.S. adults ages 40 to 74—or 41 million people—had prediabetes
in 2000. New data suggest that at least 54 million U.S. adults had pre-diabetes in 2002.
If you have pre-diabetes, you have a higher risk of developing type 2 diabetes, formerly called adultonset
diabetes or noninsulin-dependent diabetes. Studies have shown that most people with prediabetes
go on to develop type 2 diabetes within 10 years, unless they lose 5 to 7 percent of their
body weight—which is about 10 to 15 pounds for someone who weighs 200 pounds—by making
modest changes in their diet and level of physical activity. People with pre-diabetes also have a
higher risk of heart disease.
Type 2 diabetes is sometimes defined as the form of diabetes that develops when the body does not
respond properly to insulin, as opposed to type 1 diabetes, in which the pancreas makes no insulin
at all. At first, the pancreas keeps up with the added demand by producing more insulin. In time,
however, it loses the ability to secrete enough insulin in response to meals.
Insulin resistance can also occur in people who have type 1 diabetes, especially if they are
causes insulin resistance?
Because insulin resistance tends to run
in families, we know that genes are partly responsible. Excess weight also contributes
to insulin resistance because too much fat interferes with muscles' ability to
use insulin. Lack of exercise further reduces muscles' ability to use insulin.
people with insulin resistance and high blood glucose have excess weight around
the waist, high LDL (bad) blood cholesterol levels, low HDL (good) cholesterol
levels, high levels of triglycerides (another fat in the blood), and high blood
pressure, all conditions that also put the heart at risk. This combination of
problems is referred to as the metabolic syndrome, or the insulin resistance syndrome
(formerly called Syndrome X).
Metabolic syndrome is defined by the National Cholesterol Education Program as the presence
of any three of the following conditions:
excess weight around the waist (waist measurement of more than 40 inches for men and
more than 35 inches for women)
high levels of triglycerides (150 mg/dL or higher)
low levels of HDL, or "good," cholesterol (below 40 mg/dL for men and below 50 mg/dL
high blood pressure (130/85 mm Hg or higher)
high fasting blood glucose levels (110 mg/dL or higher)
Source: National Cholesterol Education Program, Third Report of the Expert Panel on Detection, Evaluation, and Treatment
of High Blood Cholesterol in Adults (Adult Treatment Panel III), National Heart, Lung, and Blood Institute, National Institutes
of Health, May 2001.
Note: Other definitions of similar conditions have been developed by the World Health Organization and the Association of
are the symptoms of insulin resistance and pre-diabetes?
resistance and pre-diabetes usually have no symptoms. You may have one or both
conditions for several years without noticing anything. If you have a severe form
of insulin resistance, you may get dark patches of skin, usually on the back of
your neck. Sometimes people get a dark ring around their neck. Other possible
sites for these dark patches include elbows, knees, knuckles, and armpits. This
condition is called acanthosis nigricans.
you have a mild or moderate form of insulin resistance, blood tests may show normal
or high blood glucose and high levels of insulin at the same time.
you have insulin resistance or pre-diabetes?
Anyone 45 years or
older should consider getting tested for diabetes. If you are overweight and aged
45 or older, it is strongly recommended that you get tested. You should consider
getting tested if you are younger than 45, overweight, and have one or more of
the following risk factors:
history of diabetes
HDL cholesterol and high triglycerides
of gestational diabetes (diabetes during pregnancy) or gave birth to a baby weighing
more than 9 pounds
group background (African American, American Indian, Hispanic American/Latino,
or Asian American/Pacific Islander)
and pre-diabetes can be detected with one of the following tests:
fasting glucose test measures your blood glucose after you have gone overnight
without eating. This test is most reliable when done in the morning. Fasting glucose
levels of 100 to 125 mg/dL are above normal but not high enough to be called diabetes.
This condition is called pre-diabetes or impaired fasting glucose, and it suggests
that you have probably had insulin resistance for some time. IFG is considered
a pre-diabetic state, meaning that you are more likely to develop diabetes but
do not have it yet.
glucose tolerance test measures your blood glucose after an overnight fast
and 2 hours after you drink a sweet liquid provided by the doctor or laboratory.
If your blood glucose falls between 140 and 199 mg/dL 2 hours after drinking the
liquid, your glucose tolerance is above normal but not high enough for diabetes.
This condition, also a form of pre-diabetes, is called impaired glucose tolerance
and, like IFG, it points toward a history of insulin resistance and a risk for
These tests give only indirect evidence of insulin resistance. The test that most accurately measures
insulin resistance is too complicated and expensive to use as a screening tool in most doctors’
offices. The test, called the euglycemic clamp, is a research tool that helps scientists learn more
about sugar metabolism problems. Insulin resistance can also be assessed with measurement of
fasting insulin. If conventional tests show that you have IFG or IGT, your doctor may suggest
changes in diet and exercise to reduce your risk of developing diabetes.
If your blood glucose is higher than normal but lower than the diabetes range, have your blood
glucose checked in 1 to 2 years.
Lab Tests and What They Show
Blood glucose. High blood glucose may be a sign that your body does not have
enough insulin or does not use it well. However, a fasting measurement or oral
glucose tolerance test gives more precise information.
Insulin. An insulin measurement helps determine whether a high blood glucose
reading is the result of insufficient insulin or poor use of insulin.
Fasting glucose. Your blood glucose level should be lower after several hours
without eating. After an overnight fast, the normal level is below 100 mg/dL. If it is in
the 100 to 125 mg/dL range, you have impaired fasting glucose or pre-diabetes. A
result of 126 or higher, if confirmed on a repeat test, indicates diabetes.
Glucose tolerance. Your blood glucose level will be higher after drinking a sugar
solution, but it should still be below 140 mg/dL 2 hours after the drink. If it is higher
than normal (in the 140 to 199 mg/dL range) 2 hours after drinking the solution, you
have IGT or pre-diabetes, which is another strong indication that your body has
trouble using glucose. A level of 200 or higher, if confirmed, means diabetes is
you reverse insulin resistance?
Yes. Physical activity and weight
loss make the body respond better to insulin. By losing weight and being more
physically active, you may avoid developing type 2 diabetes. In fact, a major
study has verified the benefits of healthy lifestyle changes and weight loss.
In 2001, the National Institutes of Health completed the Diabetes Prevention Program
(DPP), a clinical trial designed to find the most effective ways of preventing
type 2 diabetes in overweight people with pre-diabetes. The researchers found
that lifestyle changes reduced the risk of diabetes by 58 percent. Also, many
people with pre-diabetes returned to normal blood glucose levels.
main goal in treating insulin resistance and pre-diabetes is to help your body
relearn to use insulin normally. You can do several things to help reach this
Active and Eat Well
Physical activity helps your muscle cells use
blood glucose because they need it for energy. Exercise makes those cells more
sensitive to insulin.
DPP confirmed that people who follow a low-fat, low-calorie diet and who increase
activities such as walking briskly or riding a bike for 30 minutes, five times
a week, have a far smaller risk of developing diabetes than people who do not
exercise regularly. The DPP also reinforced the importance of a low-calorie, low-fat
diet. Following a low-calorie, low-fat diet can provide two benefits. If you are
overweight, one benefit is that limiting your calorie and fat intake can help
you lose weight. DPP participants who lost weight were far less likely to develop
diabetes than others in the study who remained at an unhealthy weight. Increasing
your activity and following a low-calorie, low-fat diet can also improve your
blood pressure and cholesterol levels and has many other health benefits.
have established some numbers to help people set goals that will reduce their
risk of developing glucose metabolism problems.
Body mass index (BMI) is a measure used to evaluate body weight relative to height.
You can use BMI to find out whether you are underweight, normal weight, overweight,
or obese. Use the Body Mass Index Table to find your BMI.
your height in the left-hand column.
across in the same row to the number closest to your weight.
number at the top of that column is your BMI. Check the word above your BMI to
see whether you are normal weight, overweight, or obese. If you are overweight
or obese, talk with your doctor about ways to lose weight to reduce your risk
Mass Index Table
a printer-friendly version of this table, use the pdf.*
Adapted from Clinical Guidelines on the Identification, Evaluation, and Treatment
of Overweight and Obesity in Adults: The Evidence Report.
pressure. Blood pressure is expressed as two numbers that represent pressure
in your blood vessels when your heart is beating (systolic pressure) and when
it is resting (diastolic pressure). The numbers are usually written with a slash--for
example, 140/90, which is expressed as "140 over 90." For the general
population, blood pressure below 130/85 is considered normal, although people
whose blood pressure is slightly elevated and who have no additional risk factors
for heart disease may be advised to make lifestyle changes--that is, diet and
exercise--rather than take blood pressure medicines. People who have diabetes,
however, should take whatever steps necessary, including lifestyle changes and
medicine, to reach a blood pressure goal of below 130/80.
- Cholesterol. Your cholesterol is usually reported with three values: low density lipoprotein
(LDL) cholesterol, high density lipoprotein (HDL) cholesterol, and total cholesterol.
LDL cholesterol is sometimes called "bad" cholesterol, while HDL cholesterol
is called "good" cholesterol. To lower your risk of cardiovascular problems
if you have diabetes, you should try to keep your LDL cholesterol below 100 and
your total cholesterol below 200.
If you have metabolic syndrome, your doctor
may recommend weight loss with diet and exercise, as well as medication to lower
your cholesterol and blood pressure levels.
In addition to increasing your risk of cancer and cardiovascular
disease, smoking contributes to insulin resistance. Quitting smoking is not easy,
but it could be the single smartest thing you can do to improve your health. You
will reduce your risk for respiratory problems, lung cancer, and diabetes.
Two classes of drugs can improve response to insulin
and are used by prescription for type 2 diabetes--biguanides and thiazolidinediones.
Other medicines used for diabetes act by other mechanisms. Alpha-glucosidase inhibitors
restrict or delay the absorption of carbohydrates after eating, resulting in a
slower rise of blood glucose levels. Sulfonylureas and meglitinides increase insulin
DPP showed that the diabetes drug metformin, a biguanide, reduced the risk of
diabetes in those with pre-diabetes but was much less successful than losing weight
and increasing activity. In another study, treatment with troglitazone, a thiazolidinedione
later withdrawn from the market following reports of liver toxicity, delayed or
prevented type 2 diabetes in Hispanic women with a history of gestational diabetes.
Acarbose, an alpha-glucosidase inhibitor, has been effective in delaying development
of type 2 diabetes. Additional studies using other diabetes medicines and some
types of blood pressure medicines to prevent diabetes are under way. No drug has
been approved by the Food and Drug Administration (FDA) specifically for insulin
resistance or pre-diabetes.
Hope through Research
Researchers sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases
conducted the DPP to find the most effective ways to prevent or delay the onset of type 2 diabetes.
Volunteers were recruited from groups known to be at particularly high risk for IGT and type 2
diabetes. The study was designed to compare the effectiveness of lifestyle changes (weight loss
through exercise and diet) with drug therapy (metformin). A control group received a placebo and
information on diet and exercise. Participants assigned to the intensive lifestyle intervention reduced
their risk of getting type 2 diabetes by 58 percent over 3 years. Participants treated with metformin
reduced their risk by 31 percent. Metformin is not currently approved for use in preventing diabetes,
but the FDA may determine whether to make diabetes prevention an added indication for this drug.
In any event, the DPP demonstrates that a healthy diet and exercise are the most effective treatment
for insulin resistance and the prediabetic states of IFG and IGT.
Points to Remember
- Glucose is the simple sugar that is the main source of energy for the body’s cells.
- Insulin helps cells take in blood glucose and convert it to energy.
- If you have insulin resistance, your body’s cells do not respond well to insulin.
- Insulin resistance is a stepping-stone to type 2 diabetes.
- Lack of exercise and excess weight contribute to insulin resistance.
- Engaging in moderate physical activity and maintaining proper weight can help prevent insulin
- Insulin resistance plays a role in the development of cardiovascular disease, which damages
the heart and blood vessels.
- Controlling blood pressure and LDL cholesterol and not smoking can also help prevent
- The Diabetes Prevention Program confirmed that exercise and a low-calorie, low-fat diet are
the best ways to prevent type 2 diabetes.
Diabetes Information Clearinghouse
1 Information Way
National Diabetes Information Clearinghouse (NDIC) is a service of the National
Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). The NIDDK is
part of the National Institutes of Health under the U.S. Department of Health
and Human Services. Established in 1978, the clearinghouse provides information
about diabetes to people with diabetes and to their families, health care professionals,
and the public. NDIC answers inquiries, develops and distributes publications,
and works closely with professional and patient organizations and Government agencies
to coordinate resources about diabetes.
produced by the clearinghouse are carefully reviewed by both NIDDK scientists
and outside experts. This fact sheet was reviewed by George A. Bray, M.D., Pennington
Biomedical Research Center, Louisiana State University; and Richard F. Hamman,
M.D., Dr.P.H., Department of Preventive Medicine and Biometrics, University of
Colorado Health Sciences Center.
Department of Health and Human Services
National Institutes of Health
Publication No. 04-4893