Insulin Resistance 

and Prediabetes 

National Diabetes Information Clearinghouse 

 

U.S. Department 

of Health and 

Human Services 

NATIONAL 

INSTITUTES 

OF HEALTH 

What is insulin resistance? 

Insulin resistance is a condition in which the 

body produces insulin but does not use it 

properly. Insulin, a hormone made by the 

pancreas, helps the body use glucose for 

energy. Glucose is a form of sugar that is 

the body’s main source of energy. 

The body’s digestive system breaks food 

down into glucose, which then travels in the 

bloodstream to cells throughout the body. 

Glucose in the blood is called blood glucose, 

also known as blood sugar. As the blood 

glucose level rises after a meal, the pancreas 

releases insulin to help cells take in and use 

the glucose. 

When people are insulin resistant, their 

muscle, fat, and liver cells do not respond 

properly to insulin. As a result, their bodies need more insulin to help glucose enter 

cells. The pancreas tries to keep up with this 

increased demand for insulin by producing 

more. Eventually, the pancreas fails to keep 

up with the body’s need for insulin. Excess 

glucose builds up in the bloodstream, setting 

the stage for diabetes. Many people with 

insulin resistance have high levels of both 

glucose and insulin circulating in their blood 

at the same time. 

Insulin resistance increases the chance of 

developing type 2 diabetes and heart disease. 

Learning about insulin resistance is the first 

step toward making lifestyle changes that 

can help prevent diabetes and other health 

problems. 

What causes insulin 

resistance? 

Scientists have identified specific genes that 

make people more likely to develop insulin 

resistance and diabetes. Excess weight and 

lack of physical activity also contribute to 

insulin resistance. 

Many people with insulin resistance and 

high blood glucose have other conditions 

that increase the risk of developing type 2 

diabetes and damage to the heart and blood 

vessels, also called cardiovascular disease. 

These conditions include having excess 

weight around the waist, high blood pressure, and abnormal levels of cholesterol and 

triglycerides in the blood. Having several of 

these problems is called metabolic syndrome 

or insulin resistance syndrome, formerly 

called syndrome X. 
Metabolic Syndrome 

Metabolic syndrome is defined as the 

presence of any three of the following 

conditions: 

• waist measurement of 40 inches 

or more for men and 35 inches or 

more for women 

• triglyceride levels of 150 milligrams 

per deciliter (mg/dL) or above, 

or taking medication for elevated 

triglyceride levels 

• HDL, or “good,” cholesterol level 

below 40 mg/dL for men and below 

50 mg/dL for women, or taking 

medication for low HDL levels 

• blood pressure levels of 130/85 or 

above, or taking medication for 

elevated blood pressure levels 

• fasting blood glucose levels of 

100 mg/dL or above, or taking 

medication for elevated blood glucose levels 

Source: Grundy SM, et al. Diagnosis and 

management of the metabolic syndrome: an 

American Heart Association/National Heart, 

Lung, and Blood Institute scientific statement. 

Circulation. 2005;112:2735–2752. 

Similar definitions have been developed by the 

World Health Organization and the American 

Association of Clinical Endocrinologists. 

What is prediabetes? 

Prediabetes is a condition in which blood 

glucose levels are higher than normal but 

not high enough for a diagnosis of diabetes. 

This condition is sometimes called impaired 

fasting glucose (IFG) or impaired glucose 

tolerance (IGT), depending on the test used 

to diagnose it. The U.S. Department of 

Health and Human Services estimates that 

about one in four U.S. adults aged 20 years 

or older—or 57 million people—had prediabetes in 2007. 

People with prediabetes are at increased 

risk of developing type 2 diabetes, formerly 

called adult-onset diabetes or noninsulindependent diabetes. 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 

little or no insulin. 

Studies have shown that most people with 

prediabetes develop type 2 diabetes within 

10 years, unless they lose 5 to 7 percent of 

their body weight—about 10 to 15 pounds 

for someone who weighs 200 pounds—by 

making changes in their diet and level of 

physical activity. People with prediabetes 

also are at increased risk of developing cardiovascular disease. 

What are the symptoms 

of insulin resistance and 

prediabetes? 

Insulin resistance and prediabetes usually 

have no symptoms. People may have one 

or both conditions for several years without 

noticing anything. People with a severe form 

of insulin resistance may have dark patches 

of skin, usually on the back of the neck. 

Sometimes people have a dark ring around 

their neck. Other possible sites for dark 

patches include elbows, knees, knuckles, and 

armpits. This condition is called acanthosis 

nigricans. 

2 Insulin Resistance and Prediabetes 
 

 

 

 

 

How are insulin resistance 

and prediabetes diagnosed? 

Health care providers use blood tests to 

determine whether a person has prediabetes 

but do not usually test for insulin resistance. 

Insulin resistance can be assessed by measuring the level of insulin in the blood. However, the test that most accurately measures 

insulin resistance, called the euglycemic 

clamp, is too costly and complicated to be 

used in most doctors’ offices. The clamp is a 

research tool used by scientists to learn more 

about glucose metabolism. If tests indicate 

prediabetes or metabolic syndrome, insulin 

resistance most likely is present. 

Diabetes and prediabetes can be detected 

with one of the following tests: 

• Fasting glucose test. This test measures 

blood glucose in people who have not 

eaten anything for at least 8 hours. 

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 prediabetes 

or IFG. People with IFG often have 

had insulin resistance for some time. 

They are much more likely to develop 

diabetes than people with normal blood 

glucose levels. 

• Glucose tolerance test. This test measures blood glucose after people fast for 

at least 8 hours and 2 hours after they 

drink a sweet liquid provided by a doctor or laboratory. A blood glucose level 

between 140 and 199 mg/dL means glucose tolerance is not normal but is not 

high enough for a diagnosis of diabetes. 

This form of prediabetes is called IGT 

and, like IFG, it points toward a history of insulin resistance and a risk for 

developing diabetes. 

People whose test results indicate they have 

prediabetes should have their blood glucose 

levels checked again in 1 to 2 years. 

Risk Factors for Prediabetes 

and Type 2 Diabetes 

The American Diabetes Association recommends that testing to detect prediabetes and type 2 diabetes be considered in 

adults without symptoms who are overweight or obese and have one or more 

additional risk factors for diabetes. In 

those without these risk factors, testing 

should begin at age 45. 

Risk factors for prediabetes and 

diabetes—in addition to being overweight or obese or being age 45 or 

older—include the following: 

• being physically inactive 

• having a parent or sibling with diabetes 

• having a family background that is 

African American, Alaska Native, 

American Indian, Asian American, 

Hispanic/Latino, or Pacific Islander 

• giving birth to a baby weighing more 

than 9 pounds or being diagnosed 

with gestational diabetes—diabetes 

first found during pregnancy 

• having high blood pressure—140/90 

or above—or being treated for high 

blood pressure 

• having an HDL, or “good,” cholesterol level below 35 mg/dL or a 

triglyceride level above 250 mg/dL 

• having polycystic ovary syndrome, 

also called PCOS 

• having impaired fasting glucose 

(IFG) or impaired glucose tolerance 

(IGT) on previous testing 

• having other conditions associated with insulin resistance, such 

as severe obesity or acanthosis 

nigricans 

• having a history of cardiovascular 

disease 

If test results are normal, testing should 

be repeated at least every 3 years. 

Health care providers may recommend 

more frequent testing depending on 

initial results and risk status. 

3 Insulin Resistance and Prediabetes 
 

Can insulin resistance and 

prediabetes be reversed? 

Yes. Physical activity and weight loss help 

the body respond better to insulin. By losing weight and being more physically active, 

people with insulin resistance or prediabetes 

may avoid developing type 2 diabetes. 

The Diabetes Prevention Program (DPP) 

and other large studies have shown that 

people with prediabetes can often prevent 

or delay diabetes if they lose a modest 

amount of weight by cutting fat and calorie 

intake and increasing physical activity—for 

example, walking 30 minutes a day 5 days 

a week. Losing just 5 to 7 percent of body 

weight prevents or delays diabetes by nearly 

60 percent. In the DPP, people aged 60 or 

older who made lifestyle changes lowered 

their chances of developing diabetes by 

70 percent. Many participants in the lifestyle 

intervention group returned to normal blood 

glucose levels and lowered their risk for 

developing heart disease and other problems 

associated with diabetes. The DPP also 

showed that the diabetes drug metformin 

reduced the risk of developing diabetes by 

31 percent. 

People with insulin resistance or prediabetes 

can help their body use insulin normally 

by being physically active, making wise 

food choices, and reaching and maintaining a healthy weight. Physical activity helps 

muscle cells use blood glucose for energy by 

making the cells more sensitive to insulin. 

Body Mass Index (BMI) 

BMI is a measurement of body weight 

relative to height. Adults aged 20 or 

older can use the BMI table on page 5 to 

find out whether they are normal weight, 

overweight, obese, or extremely obese. 

To use the table, follow these steps: 

• Find the person’s height in the lefthand column. 

• Move across the row to the number 

closest to that person’s weight. 

• Check the number at the top of that 

column. 

The number at the top of the column is 

the person’s BMI. The words above the 

BMI number indicate whether the person is normal weight, overweight, obese, 

or extremely obese. People who are 

overweight, obese, or extremely obese 

should consider talking with a doctor 

about ways to lose weight to reduce the 

risk of diabetes. 

The BMI table has certain limitations. 

It may overestimate body fat in athletes 

and others who have a muscular build 

and underestimate body fat in older 

adults and others who have lost muscle. 

BMI for children and teens must be 

determined based on age and sex in 

addition to height and weight. Information about BMI in children and teens, 

including a BMI calculator, is available 

from the Centers for Disease Control 

and Prevention (CDC) at www.cdc.gov/ 

nccdphp/dnpa/bmi. The CDC website 

also has a BMI calculator for adults. 

4 Insulin Resistance and Prediabetes 
Body Mass Index Table

Normal Overweight Obese Extreme Obesity 

BMI	 19	 20	 21	 22	 23	 24	 25	 26	 27	 28	 29	 30	 31	 32	 33	 34	 35	 36	 37	 38	 39	 40	 41	 42	 43	 44	 45	 46	 47	 48	 49	 50	 51	 52	 53	 54 Height Body Weight(inches) (pounds) 58	 91	 96	 100	 105	 110	115	 119	 124	 129	 134	 138	 143	 148	 153	 158	 162	 167	 172	 177	 181	 186	 191	 196	 201	 205	 210	 215	 220	 224	 229	 234	 239	 244	 248	 253	 25859	 94	 99	 104	 109	 114	119	 124	 128	 133	 138	 143	 148	 153	 158	 163	 168	 173	 178	 183	 188	 193	 198	 203	 208	 212	 217	 222	 227	 232	 237	 242	 247	 252	 257	 262	 26760	 97	 102	 107	 112	 118	123	 128	 133	 138	 143	 148	 153	 158	 163	 168	 174	 179	 184	 189	 194	 199	 204	 209	 215	 220	 225	 230	 235	 240	 245	 250	 255	 261	 266	 271	 27661	 100	 106	 111	 116	 122	127	 132	 137	 143	 148	 153	 158	 164	 169	 174	 180	 185	 190	 195	 201	 206	 211	 217	 222	 227	 232	 238	 243	 248	 254	 259	 264	 269	 275	 280	 28562	 104	 109	 115	 120	 126	131	 136	 142	 147	 153	 158	 164	 169	 175	 180	 186	 191	 196	 202	 207	 213	 218	 224	 229	 235	 240	 246	 251	 256	 262	 267	 273	 278	 284	 289	 29563	 107	 113	 118	 124	 130	135	 141	 146	 152	 158	 163	 169	 175	 180	 186	 191	 197	 203	 208	 214	 220	 225	 231	 237	 242	 248	 254	 259	 265	 270	 278	 282	 287	 293	 299	 30464	 110	 116	 122	 128	 134	140	 145	 151	 157	 163	 169	 174	 180	 186	 192	 197	 204	 209	 215	 221	 227	 232	 238	 244	 250	 256	 262	 267	 273	 279	 285	 291	 296	 302	 308	 31465	 114	 120	 126	 132	 138	144	 150	 156	 162	 168	 174	 180	 186	 192	 198	 204	 210	 216	 222	 228	 234	 240	 246	 252	 258	 264	 270	 276	 282	 288	 294	 300	 306	 312	 318	 32466	 118	 124	 130	 136	 142	148	 155	 161	 167	 173	 179	 186	 192	 198	 204	 210	 216	 223	 229	 235	 241	 247	 253	 260	 266	 272	 278	 284	 291	 297	 303	 309	 315	 322	 328	 33467	 121	 127	 134	 140	 146	153	 159	 166	 172	 178	 185	 191	 198	 204	 211	 217	 223	 230	 236	 242	 249	 255	 261	 268	 274	 280	 287	 293	 299	 306	 312	 319	 325	 331	 338	 34468	 125	 131	 138	 144	 151	158	 164	 171	 177	 184	 190	 197	 203	 210	 216	 223	 230	 236	 243	 249	 256	 262	 269	 276	 282	 289	 295	 302	 308	 315	 322	 328	 335	 341	 348	 35469	 128	 135	 142	 149	 155	162	 169	 176	 182	 189	 196	 203	 209	 216	 223	 230	 236	 243	 250	 257	 263	 270	 277	 284	 291	 297	 304	 311	 318	 324	 331	 338	 345	 351	 358	 36570	 132	 139	 146	 153	 160	167	 174	 181	 188	 195	 202	 209	 216	 222	 229	 236	 243	 250	 257	 264	 271	 278	 285	 292	 299	 306	 313	 320	 327	 334	 341	 348	 355	 362	 369	 37671	 136	 143	 150	 157	 165	172	 179	 186	 193	 200	 208	 215	 222	 229	 236	 243	 250	 257	 265	 272	 279	 286	 293	 301	 308	 315	 322	 329	 338	 343	 351	 358	 365	 372	 379	 38672	 140	 147	 154	 162	 169	177	 184	 191	 199	 206	 213	 221	 228	 235	 242	 250	 258	 265	 272	 279	 287	 294	 302	 309	 316	 324	 331	 338	 346	 353	 361	 368	 375	 383	 390	 39773	 144	 151	 159	 166	 174	182	 189	 197	 204	 212	 219	 227	 235	 242	 250	 257	 265	 272	 280	 288	 295	 302	 310	 318	 325	 333	 340	 348	 355	 363	 371	 378	 386	 393	 401	 40874	 148	 155	 163	 171	 179	186	 194	 202	 210	 218	 225	 233	 241	 249	 256	 264	 272	 280	 287	 295	 303	 311	 319	 326	 334	 342	 350	 358	 365	 373	 381	 389	 396	 404	 412	 42075	 152	 160	 168	 176	 184	192	 200	 208	 216	 224	 232	 240	 248	 256	 264	 272	 279	 287	 295	 303	 311	 319	 327	 335	 343	 351	 359	 367	 375	 383	 391	 399	 407	 415	 423	 43176	 156	 164	 172	 180	 189	197	 205	 213	 221	 230	 238	 246	 254	 263	 271	 279	 287	 295	 304	 312	 320	 328	 336	 344	 353	 361	 369	 377	 385	 394	 402	 410	 418	 426	 435	 443 

5 Insulin Resistance and Prediabetes 

Source: Adapted from Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults: The Evidence Report, National Institutes of Health, 1998. 
Can medicines help 

reverse insulin resistance 

or prediabetes? 

Clinical trials have shown that people at high 

risk for developing diabetes can be given 

treatments that delay or prevent onset of 

diabetes. The first therapy should always be 

an intensive lifestyle modification program 

because weight loss and physical activity are 

much more effective than any medication at 

reducing diabetes risk. 

Several drugs have been shown to reduce 

diabetes risk to varying degrees. No drug 

is approved by the U.S. Food and Drug 

Administration to treat insulin resistance or 

prediabetes or to prevent type 2 diabetes. 

The American Diabetes Association recommends that metformin is the only drug that 

should be considered for use in diabetes 

prevention. Other drugs that have delayed 

diabetes have side effects or haven’t shown 

long-lasting benefit. Metformin use was recommended only for very high-risk individuals who have both forms of prediabetes (IGT 

and IFG), have a BMI of at least 35, and are 

younger than age 60. In the DPP, metformin 

was shown to be most effective in younger, 

heavier patients. 

Points to Remember 

• Insulin resistance is a condition in 

which the body’s cells do not use 

insulin properly. Insulin helps cells 

use blood glucose for energy. 

• Insulin resistance increases the 

risk of developing prediabetes, 

type 2 diabetes, and cardiovascular 

disease. 

• Prediabetes is a condition in which 

blood glucose levels are higher than 

normal but not high enough for a 

diagnosis of diabetes. 

• Causes of insulin resistance and 

prediabetes include genetic factors, 

excess weight, and lack of physical 

activity. 

• Being physically active, making 

wise food choices, and reaching 

and maintaining a healthy weight 

can help prevent or reverse insulin 

resistance and prediabetes. 

• The Diabetes Prevention Program 

(DPP) study confirmed that people 

at risk for developing type 2 diabetes can prevent or delay the onset of 

diabetes by losing 5 to 7 percent of 

their body weight through regular 

physical activity and a diet low in fat 

and calories. 

6 Insulin Resistance and Prediabetes 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hope through Research 

Researchers continue to follow DPP participants to learn about the long-term effects of 

the study. Other research sponsored by the 

National Institutes of Health builds on the 

findings from the DPP, including research 

focusing on lowering diabetes risk in children. Once considered an adult disease, 

type 2 diabetes is becoming more common in 

children, and researchers are seeking ways to 

reverse this trend. 

The National Institute of Diabetes and 

Digestive and Kidney Diseases (NIDDK) 

sponsors the HEALTHY study, which is 

part of a broad research initiative called 

STOPP T2D (Studies to Treat or Prevent 

Pediatric Type 2 Diabetes). The study seeks 

to improve the treatment and prevention of 

type 2 diabetes in youth, exploring the roles 

of nutrition, physical activity, and behavior 

change in lowering risk for type 2 diabetes 

in children. The participating 42 middle 

schools are randomly assigned to a program 

group implementing changes or a comparison group. Students in the program group 

have healthier choices from the cafeteria 

and vending machines; longer, more intense 

periods of physical activity; and activities and 

awareness campaigns that promote longterm healthy behaviors. Results from the 

HEALTHY study are expected in 2009. 

The NIDDK also sponsors the TODAY 

(Treatment Options for Type 2 Diabetes in 

Adolescents and Youth) study, which focuses 

on treatment of type 2 diabetes in children 

and teens at 13 sites. The TODAY study 

will evaluate the effects of three treatment 

approaches on control of blood glucose 

levels, insulin production, insulin resistance, 

and other outcomes. Each approach involves 

medication, but one of the three treatment 

groups will also receive an intensive lifestyle 

intervention to help the participants lose 

weight and increase physical fitness. More 

information about the TODAY study is available at www.todaystudy.org. 

Participants in clinical trials can play a more 

active role in their own health care, gain 

access to new research treatments before 

they are widely available, and help others 

by contributing to medical research. For 

information about current studies, visit 

www.ClinicalTrials.gov. 

For More Information 

For more information about the DPP and 

the risk of developing diabetes, see these 

publications: 

• Diabetes Prevention Program 

• Am I at Risk for Type 2 Diabetes? 

These publications are available at 

www.diabetes.niddk.nih.gov or by 

calling 1–800–860–8747. 

American Diabetes Association 

1701 North Beauregard Street 

Alexandria, VA 22311 

Phone: 1–800–DIABETES (342–2383) 

Email: AskADA@diabetes.org 

Internet: www.diabetes.org 

National Diabetes Education Program 

1 Diabetes Way 

Bethesda, MD 20814–9692 

Phone: 1–888–693–NDEP (6337) 

TTY: 1–866–569–1162 

Fax: 703–738–4929 

Email: ndep@mail.nih.gov 

Internet: www.ndep.nih.gov 

National Heart, Lung, and Blood Institute 

Information Center 

P.O. Box 30105 

Bethesda, MD 20824–0105 

Phone: 301–592–8573 

Fax: 301–592–8563 

Email: nhlbiinfo@nhlbi.nih.gov 

Internet: www.nhlbi.nih.gov 

7 Insulin Resistance and Prediabetes 
 

 

 

 

 

 

 

 

 

 

 

 

 

You may also find additional information about this 

topic by visiting MedlinePlus at www.medlineplus.gov. 

This publication may contain information about medications. When prepared, this publication included 

the most current information available. For updates 

or for questions about any medications, contact 

the U.S. Food and Drug Administration toll-free at 

1–888–INFO–FDA (463–6332) or visit www.fda.gov. 

Consult your doctor for more information. 

The U.S. Government does not endorse or favor any 

specific commercial product or company. Trade, 

proprietary, or company names appearing in this 

document are used only because they are considered 

necessary in the context of the information provided. 

If a product is not mentioned, the omission does not 

mean or imply that the product is unsatisfactory. 

National Diabetes 

Information Clearinghouse 

1 Information Way 

Bethesda, MD 20892–3560 

Phone: 1–800–860–8747 

TTY: 1–866–569–1162 

Fax: 703–738–4929 

Email: ndic@info.niddk.nih.gov 

Internet: www.diabetes.niddk.nih.gov 

The 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 of 

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. The NDIC 

answers inquiries, develops and distributes 

publications, and works closely with professional 

and patient organizations and Government 

agencies to coordinate resources about diabetes. 

Publications produced by the Clearinghouse are 

carefully reviewed by both NIDDK scientists and 

outside experts. This publication was originally 

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. 

This publication is not copyrighted. The Clearinghouse 

encourages users of this fact sheet to duplicate and 

distribute as many copies as desired. 

This fact sheet is also available at 

www.diabetes.niddk.nih.gov. 

U.S.	DEPARTMENT	OF	HEALTH	 

AND	HUMAN	SERVICES 

National	Institutes	of	Health 

NIH Publication No. 09–4893 

October 2008