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Insulin Resistance and Prediabetes

On this page:

What is insulin?

Insulin is a hormone made in the pancreas, an organ located behind the stomach. The pancreas contains clusters of cells called islets. Beta cells within the islets make insulin and release it into the blood.

Insulin plays a major role in metabolism—the way the body uses digested food for energy. The digestive tract breaks down carbohydrates—sugars and starches found in many foods—into glucose. Glucose is a form of sugar that enters the bloodstream. With the help of insulin, cells throughout the body absorb glucose and use it for energy.

Insulin’s Role in Blood Glucose Control

When blood glucose levels rise after a meal, the pancreas releases insulin into the blood. Insulin and glucose then travel in the blood to cells throughout the body.

  • Insulin helps muscle, fat, and liver cells absorb glucose from the bloodstream, lowering blood glucose levels.
  • Insulin stimulates the liver and muscle tissue to store excess glucose. The stored form of glucose is called glycogen.
  • Insulin also lowers blood glucose levels by reducing glucose production in the liver.

In a healthy person, these functions allow blood glucose and insulin levels to remain in the normal range.

Drawing of a male torso showing the location of the liver and the pancreas with an enlargement of a pancreatic islet containing beta cells.
The pancreas contains clusters of cells called islets. Beta cells within the islets make insulin and release it into the blood.

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What is insulin resistance?

Insulin resistance is a condition in which the body produces insulin but does not use it effectively. When people have insulin resistance, glucose builds up in the blood instead of being absorbed by the cells, leading to type 2 diabetes or prediabetes.

Most people with insulin resistance don’t know they have it for many years—until they develop type 2 diabetes, a serious, lifelong disease. The good news is that if people learn they have insulin resistance early on, they can often prevent or delay diabetes by making changes to their lifestyle.

Insulin resistance can lead to a variety of serious health disorders. The section “What is metabolic syndrome?” provides more information about other health disorders linked to insulin resistance.

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What happens with insulin resistance?

In insulin resistance, muscle, fat, and liver cells do not respond properly to insulin and thus cannot easily absorb glucose from the bloodstream. As a result, the body needs higher levels of insulin to help glucose enter cells.

The beta cells in the pancreas try to keep up with this increased demand for insulin by producing more. As long as the beta cells are able to produce enough insulin to overcome the insulin resistance, blood glucose levels stay in the healthy range.

Over time, insulin resistance can lead to type 2 diabetes and prediabetes because the beta cells fail to keep up with the body’s increased need for insulin. Without enough insulin, excess glucose builds up in the bloodstream, leading to diabetes, prediabetes, and other serious health disorders.

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What causes insulin resistance?

Although the exact causes of insulin resistance are not completely understood, scientists think the major contributors to insulin resistance are excess weight and physical inactivity.

Excess Weight

Some experts believe obesity, especially excess fat around the waist, is a primary cause of insulin resistance. Scientists used to think that fat tissue functioned solely as energy storage. However, studies have shown that belly fat produces hormones and other substances that can cause serious health problems such as insulin resistance, high blood pressure, imbalanced cholesterol, and cardiovascular disease (CVD).

Belly fat plays a part in developing chronic, or long-lasting, inflammation in the body. Chronic inflammation can damage the body over time, without any signs or symptoms. Scientists have found that complex interactions in fat tissue draw immune cells to the area and trigger low-level chronic inflammation. This inflammation can contribute to the development of insulin resistance, type 2 diabetes, and CVD. Studies show that losing the weight can reduce insulin resistance and prevent or delay type 2 diabetes.

Physical Inactivity

Many studies have shown that physical inactivity is associated with insulin resistance, often leading to type 2 diabetes. In the body, more glucose is used by muscle than other tissues. Normally, active muscles burn their stored glucose for energy and refill their reserves with glucose taken from the bloodstream, keeping blood glucose levels in balance.

Studies show that after exercising, muscles become more sensitive to insulin, reversing insulin resistance and lowering blood glucose levels. Exercise also helps muscles absorb more glucose without the need for insulin. The more muscle a body has, the more glucose it can burn to control blood glucose levels.

Other Causes

Other causes of insulin resistance may include ethnicity; certain diseases; hormones; steroid use; some medications; older age; sleep problems, especially sleep apnea; and cigarette smoking.

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Does sleep matter?

Yes. Studies show that untreated sleep problems, especially sleep apnea, can increase the risk of obesity, insulin resistance, and type 2 diabetes. Night shift workers may also be at increased risk for these problems. Sleep apnea is a common disorder in which a person’s breathing is interrupted during sleep. People may often move out of deep sleep and into light sleep when their breathing pauses or becomes shallow. This results in poor sleep quality that causes problem sleepiness, or excessive tiredness, during the day.

Many people aren’t aware of their symptoms and aren’t diagnosed. People who think they might have sleep problems should talk with their health care provider.

More information about sleep problems is available from the National Heart, Lung, and Blood Institute at www.nhlbi.nih.gov/health/public/sleep.

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What is prediabetes?

Prediabetes is a condition in which blood glucose or A1C levels—which reflect average blood glucose levels—are higher than normal but not high enough for a diagnosis of diabetes. Prediabetes is becoming more common in the United States. The U.S. Department of Health and Human Services estimates that at least 78 million U.S. adults ages 20 or older had prediabetes in 2009.1 People with prediabetes are at increased risk of developing type 2 diabetes and CVD, which can lead to heart attack or stroke.

1National Diabetes Statistics, 2011. National Institute of Diabetes and Digestive and Kidney Diseases website. www.diabetes.niddk.nih.gov/dm/pubs/statistics/index.aspx. Updated February 2011. Accessed November 1, 2012.

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How does insulin resistance relate to type 2 diabetes and prediabetes?

Insulin resistance increases the risk of developing type 2 diabetes and prediabetes. Prediabetes usually occurs in people who already have insulin resistance. Although insulin resistance alone does not cause type 2 diabetes, it often sets the stage for the disease by placing a high demand on the insulin-producing beta cells. In prediabetes, the beta cells can no longer produce enough insulin to overcome insulin resistance, causing blood glucose levels to rise above the normal range.

Once a person has prediabetes, continued loss of beta cell function usually leads to type 2 diabetes. People with type 2 diabetes have high blood glucose. Over time, high blood glucose damages nerves and blood vessels, leading to complications such as heart disease, stroke, blindness, kidney failure, and lower-limb amputations.

Studies have shown that most people with prediabetes develop type 2 diabetes within 10 years, unless they change their lifestyle. Lifestyle changes include losing 5 to 7 percent of their body weight—10 to 14 pounds for people who weigh 200 pounds—by making changes in their diet and level of physical activity.

Drawing of a stoplight with the words 'Caution: Take steps to prevent type 2 diabetes now.'

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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 knowing they have them. Even without symptoms, health care providers can identify people at high risk by their physical characteristics, also known as risk factors. The section “Who should be tested for prediabetes?” lists these risk factors.

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. Dark patches may also appear on elbows, knees, knuckles, and armpits. This condition is called acanthosis nigricans.

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Who should be tested for prediabetes?

The American Diabetes Association (ADA) recommends that testing to detect prediabetes be considered in adults who are overweight or obese and have one or more additional risk factors for diabetes. The section “Body Mass Index (BMI)” explains how to determine if a person is overweight or obese. However, not everyone who is overweight will get type 2 diabetes. People without these risk factors should begin testing at age 45.

Risk factors for prediabetes—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 American
  • giving birth to a baby weighing more than 9 pounds
  • being diagnosed with gestational diabetes—diabetes that develops only during pregnancy
  • having high blood pressure—140/90 mmHg or above—or being treated for high blood pressure
  • HDL cholesterol level below 35 mg/dL or a triglyceride level above 250 mg/dL
  • having polycystic ovary syndrome (PCOS)
  • having prediabetes, impaired fasting glucose (IFG), or impaired glucose tolerance (IGT) on an earlier testing
  • having other conditions associated with insulin resistance, such as obesity or acanthosis nigricans
  • having CVD

If test results are normal, testing should be repeated at least every 3 years. Testing is important for early diagnosis. Catching prediabetes early gives people time to change their lifestyle and prevent type 2 diabetes and CVD. Health care providers may recommend more frequent testing depending on initial results and risk status.

In addition to weight, the location of excess fat on the body can be important. A waist measurement of 40 inches or more for men and 35 inches or more for women is linked to insulin resistance and increases a person’s risk for type 2 diabetes. This is true even if a person’s BMI falls within the normal range.

How to Measure the Waist

To measure the waist, a person should

  • place a tape measure around the bare abdomen just above the hip bone
  • make sure the tape is snug but isn’t digging into the skin and is parallel to the floor
  • relax, exhale, and measure

Drawing of the side silhouettes of a man and a woman with a dotted line through their waists.
Source: Adapted from www.cdc.gov.

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Body Mass Index (BMI)

Body mass index is a measurement of body weight relative to height. Adults ages 20 or older can follow the steps below using the BMI chart to find out whether they are normal weight, overweight, or obese:

  • People should find their height in the left-hand column.
  • They should move across the row to the number closest to their weight.
  • Then, they should check the number at the top of that column.

The number at the top of the column is the BMI. The words above the BMI number indicate whether that person is normal weight, overweight, or obese. People who are overweight or obese should consider talking with a health care provider or registered dietitian about ways to lose weight to reduce the risk of diabetes.

The BMI chart has certain limitations. The chart 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. A BMI calculator from the National Institutes of Health (NIH) is available at www.nhlbi.nih.gov/guidelines/obesity/BMI/bmicalc.htm.

The NIH also has a free smartphone app for calculating BMI. People can search “My BMI Calculator” on their phone to find the app. The app also provides links to information about steps people can take to bring their BMI into a healthy range.

Body Mass Index Table

Printer-friendly version (PDF, 70 KB) *  Body Mass Index Table 1 of 2
  Normal Overweight Obese
BMI 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
Height
(inches)
Body Weight (pounds)
58 91 96 100 105 110 115 119 124 129 134 138 143 148 153 158 162 167
59 94 99 104 109 114 119 124 128 133 138 143 148 153 158 163 168 173
60 97 102 107 112 118 123 128 133 138 143 148 153 158 163 168 174 179
61 100 106 111 116 122 127 132 137 143 148 153 158 164 169 174 180 185
62 104 109 115 120 126 131 136 142 147 153 158 164 169 175 180 186 191
63 107 113 118 124 130 135 141 146 152 158 163 169 175 180 186 191 197
64 110 116 122 128 134 140 145 151 157 163 169 174 180 186 192 197 204
65 114 120 126 132 138 144 150 156 162 168 174 180 186 192 198 204 210
66 118 124 130 136 142 148 155 161 167 173 179 186 192 198 204 210 216
67 121 127 134 140 146 153 159 166 172 178 185 191 198 204 211 217 223
68 125 131 138 144 151 158 164 171 177 184 190 197 203 210 216 223 230
69 128 135 142 149 155 162 169 176 182 189 196 203 209 216 223 230 236
70 132 139 146 153 160 167 174 181 188 195 202 209 216 222 229 236 243
71 136 143 150 157 165 172 179 186 193 200 208 215 222 229 236 243 250
72 140 147 154 162 169 177 184 191 199 206 213 221 228 235 242 250 258
73 144 151 159 166 174 182 189 197 204 212 219 227 235 242 250 257 265
74 148 155 163 171 179 186 194 202 210 218 225 233 241 249 256 264 272
75 152 160 168 176 184 192 200 208 216 224 232 240 248 256 264 272 279
76 156 164 172 180 189 197 205 213 221 230 238 246 254 263 271 279 287

 

Body Mass Index Table 2 of 2
  Obese Extreme Obesity
BMI 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
Height
(inches)
Body Weight (pounds)
58 172 177 181 186 191 196 201 205 210 215 220 224 229 234 239 244 248 253 258
59 178 183 188 193 198 203 208 212 217 222 227 232 237 242 247 252 257 262 267
60 184 189 194 199 204 209 215 220 225 230 235 240 245 250 255 261 266 271 276
61 190 195 201 206 211 217 222 227 232 238 243 248 254 259 264 269 275 280 285
62 196 202 207 213 218 224 229 235 240 246 251 256 262 267 273 278 284 289 295
63 203 208 214 220 225 231 237 242 248 254 259 265 270 278 282 287 293 299 304
64 209 215 221 227 232 238 244 250 256 262 267 273 279 285 291 296 302 308 314
65 216 222 228 234 240 246 252 258 264 270 276 282 288 294 300 306 312 318 324
66 223 229 235 241 247 253 260 266 272 278 284 291 297 303 309 315 322 328 334
67 230 236 242 249 255 261 268 274 280 287 293 299 306 312 319 325 331 338 344
68 236 243 249 256 262 269 276 282 289 295 302 308 315 322 328 335 341 348 354
69 243 250 257 263 270 277 284 291 297 304 311 318 324 331 338 345 351 358 365
70 250 257 264 271 278 285 292 299 306 313 320 327 334 341 348 355 362 369 376
71 257 265 272 279 286 293 301 308 315 322 329 338 343 351 358 365 372 379 386
72 265 272 279 287 294 302 309 316 324 331 338 346 353 361 368 375 383 390 397
73 272 280 288 295 302 310 318 325 333 340 348 355 363 371 378 386 393 401 408
74 280 287 295 303 311 319 326 334 342 350 358 365 373 381 389 396 404 412 420
75 287 295 303 311 319 327 335 343 351 359 367 375 383 391 399 407 415 423 431
76 295 304 312 320 328 336 344 353 361 369 377 385 394 402 410 418 426 435 443

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.

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What is metabolic syndrome?

Metabolic syndrome, also called insulin resistance syndrome, is a group of traits and medical conditions linked to overweight and obesity that puts people at risk for both CVD and type 2 diabetes. Metabolic syndrome is defined* as the presence of any three of the following:

  • large waist size—waist measurement of 40 inches or more for men and 35 inches or more for women
  • high triglycerides in the blood—triglyceride level of 150 milligrams per deciliter (mg/dL) or above, or taking medication for elevated triglyceride level
  • abnormal levels of cholesterol in the blood—HDL, or good, cholesterol level below 40 mg/dL for men and below 50 mg/dL for women, or taking medication for low HDL
  • high blood pressure—blood pressure level of 130/85 or above, or taking medication for elevated blood pressure
  • higher than normal blood glucose levels—fasting blood glucose level of 100 mg/dL or above, or taking medication for elevated blood glucose2

In addition to type 2 diabetes, metabolic syndrome has been linked to the following health disorders:

  • obesity
  • CVD
  • PCOS
  • nonalcoholic fatty liver disease
  • chronic kidney disease

However, not everyone with these disorders has insulin resistance, and some people may have insulin resistance without getting these disorders.

People who are obese or who have metabolic syndrome, insulin resistance, type 2 diabetes, or prediabetes often also have low-level inflammation throughout the body and blood clotting defects that increase the risk of developing blood clots in the arteries. These conditions contribute to increased risk for CVD.

*Similar definitions have been developed by the World Health Organization and the American Association of Clinical Endocrinologists.

2Alberti KG, Eckel RH, Grundy SM, et al. Harmonizing the metabolic syndrome: a joint interim statement of the International Diabetes Federation Task Force on Epidemiology and Prevention; National Heart, Lung, and Blood Institute; American Heart Association; World Heart Federation; International Atherosclerosis Society; and International Association for the Study of Obesity. Circulation. 2009;120:1640–1645.

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How are insulin resistance and prediabetes diagnosed?

Health care providers use blood tests to determine whether a person has prediabetes, but they do not usually test specifically 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 health care providers’ offices. The clamp is a research tool used by scientists to learn more about glucose metabolism. Research has shown that if blood tests indicate prediabetes, insulin resistance most likely is present.

Blood Tests for Prediabetes

All blood tests involve drawing blood at a health care provider’s office or commercial facility and sending the sample to a lab for analysis. Lab analysis of blood is needed to ensure test results are accurate. Glucose measuring devices used in a health care provider’s office, such as finger-stick devices, are not accurate enough for diagnosis but may be used as a quick indicator of high blood glucose.

Prediabetes can be detected with one of the following blood tests:

  • the A1C test
  • the fasting plasma glucose (FPG) test
  • the oral glucose tolerance test (OGTT)

A1C test. Sometimes called hemoglobin A1c, HbA1c, or glycohemoglobin test, this test reflects average blood glucose levels over the past 3 months. This test is the most reliable test for prediabetes, but it is not as sensitive as the other tests. In some individuals, it may miss prediabetes that could be caught by glucose tests.

Although some health care providers can quickly measure A1C in their office, that type of measurement—called a point-of-care test—is not considered reliable for diagnosis. For diagnosis of prediabetes, the A1C test should be analyzed in a laboratory using a method that is certified by the NGSP.

The A1C test can be unreliable for diagnosing prediabetes in people with certain conditions that are known to interfere with the results. Interference should be suspected when A1C results seem very different from the results of a blood glucose test. People of African, Mediterranean, or Southeast Asian descent, or people with family members with sickle cell anemia or a thalassemia, are particularly at risk of interference. People in these groups may have a less common type of hemoglobin, known as a hemoglobin variant, that can interfere with some A1C tests.

An A1C of 5.7 to 6.4 percent indicates prediabetes.

More information about the A1C test is available from the National Diabetes Information Clearinghouse (NDIC) fact sheet The A1C Test and Diabetes.

Fasting plasma 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. Prediabetes found with this test is called IFG.

Fasting glucose levels of 100 to 125 mg/dL indicate prediabetes.

OGTT. This test measures blood glucose after people have not eaten for at least 8 hours and 2 hours after they drink a sweet liquid provided by a health care provider or laboratory. Prediabetes found with this test is called IGT.

A blood glucose level between 140 and 199 mg/dL indicates prediabetes.

The following table lists the blood test levels for a diagnosis of prediabetes.

BLood test levels for diagnosis of diabetes and prediabetes
Source: Adapted from American Diabetes Association. Standards of medical care in diabetes—2012. Diabetes Care. 2012;35(Supp 1):S12, table 2.

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Understanding Test Results

A blood test indicating prediabetes means that insulin resistance has progressed to the point where the beta cells in the pancreas can no longer compensate and a person’s blood glucose levels are rising toward type 2 diabetes. The higher the test results, the greater the risk of type 2 diabetes. The level of risk also depends on an individual’s other risk factors, which are listed in the section "Who should be tested for prediabetes?"

Test numbers. For example, people with an A1C below 5.7 percent may still be at risk for diabetes if they have a family history of type 2 diabetes or have gained excess weight around the waist. People with an A1C above 6.0 percent should be considered at very high risk of developing diabetes. A level of 6.5 percent or above means a person has diabetes.

Follow up. People whose test results indicate they have prediabetes may be retested in 1 year and should consider making lifestyle changes to reduce their risk of developing type 2 diabetes.

Varying results. Although all these tests can be used to test for prediabetes, in some people one test will indicate a diagnosis of prediabetes or diabetes when another test does not. People with differing test results may be in an early stage of the disease, where blood glucose levels have not risen high enough to show on every test.

Health care providers repeat laboratory tests to confirm test results. Diabetes develops over time, so even with variations in test results, health care providers can tell when overall blood glucose levels are becoming too high.

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Can insulin resistance and prediabetes be reversed?

Yes. Physical activity and weight loss help the body respond better to insulin. The Diabetes Prevention Program (DPP) was a federally funded study of 3,234 people at high risk for diabetes.

The DPP and other large studies proved 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.

People at High Risk for Diabetes

DPP study participants were overweight and had prediabetes. Many had family members with type 2 diabetes. Prediabetes, obesity, and a family history of diabetes are strong risk factors for type 2 diabetes. About half of the DPP participants were from minority groups with high rates of diabetes, including African Americans, Alaska Natives, American Indians, Asian Americans, Hispanics/Latinos, and Pacific Islander Americans.

DPP participants also included others at high risk for developing type 2 diabetes, such as women with a history of gestational diabetes and people ages 60 and older.

Approaches to Preventing Diabetes

The DPP tested three approaches to preventing diabetes:

  • Making lifestyle changes. People in the lifestyle change group exercised, usually by walking 5 days a week for about 30 minutes a day, and lowered their intake of fat and calories.
  • Taking the diabetes medication metformin. Those who took metformin also received information about physical activity and diet.
  • Receiving education about diabetes. The third group only received information about physical activity and diet and took a placebo—a pill without medication in it.

People in the lifestyle change group showed the best outcomes. However people who took metformin also benefited. The results showed that by losing an average of 15 pounds in the first year of the study, people in the lifestyle change group reduced their risk of developing type 2 diabetes by 58 percent over 3 years.

Lifestyle change was even more effective in those ages 60 and older. People in this group reduced their risk by 71 percent.

People in the metformin group also benefited, reducing their risk by 31 percent. More information about the DPP, funded under NIH clinical trial number NCT00004992, is available at www.bsc.gwu.edu/dppleaving site icon.

Lasting Results

The Diabetes Prevention Program Outcomes Study (DPPOS) has shown that the benefits of weight loss and metformin last for at least 10 years. The DPPOS has continued to follow most DPP participants since the DPP ended in 2001. The DPPOS showed that 10 years after enrolling in the DPP

  • people in the lifestyle change group reduced their risk for developing diabetes by 34 percent
  • those in the lifestyle change group ages 60 or older had even greater benefit, reducing their risk of developing diabetes by 49 percent
  • participants in the lifestyle change group also had fewer heart and blood vessel disease risk factors, including lower blood pressure and triglyceride levels, even though they took fewer medications to control their heart disease risk
  • those in the metformin group reduced their risk of developing diabetes by 18 percent

Even though controlling weight with lifestyle changes is challenging, it produces long-term health rewards by lowering the risk for type 2 diabetes, lowering blood glucose levels, and reducing other heart disease risk factors.

For more information about the risk of developing diabetes; the DPP, funded under NIH clinical trial number NCT00004992; and the DPPOS, funded under NIH clinical trial number NCT00038727, see the following NDIC publications:

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What steps can help reverse insulin resistance and prediabetes?

By losing weight and being more physically active, people can reverse insulin resistance and prediabetes, thus preventing or delaying type 2 diabetes. People can decrease their risk by

  • eating a healthy diet and reaching and maintaining a healthy weight
  • increasing physical activity
  • not smoking
  • taking medication

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Eating, Diet, and Nutrition

Adopting healthy eating habits can help people lose a modest amount of weight and reverse insulin resistance. Experts encourage people to slowly adopt healthy eating habits that they can maintain, rather than trying extreme weight-loss solutions. People may need to get help from a dietitian or join a weight-loss program for support.

In general, people should lose weight by choosing healthy foods, controlling portions, eating less fat, and increasing physical activity. People are better able to lose weight and keep it off when they learn how to adapt their favorite foods to a healthy eating plan.

The DASH (Dietary Approaches to Stop Hypertension) eating plan, developed by the NIH, has been shown to be effective in decreasing insulin resistance when combined with weight loss and physical activity. More information on DASH is available at www.nhlbi.nih.gov/health/health-topics/topics/dash.

The U.S. Dietary Guidelines for Americans also offers healthy eating advice and tools for changing eating habits at www.choosemyplate.gov.

Dietary Supplements

Vitamin D studies show a link between people’s ability to maintain healthy blood glucose levels and having enough vitamin D in their blood. However, studies to determine the proper vitamin D levels for preventing diabetes are ongoing; no special recommendations have been made about vitamin D levels or supplements for people with prediabetes.

Currently, the Institute of Medicine (IOM), the agency that recommends supplementation levels based on current science, provides the following guidelines for daily vitamin D intake:

  • People ages 1 to 70 years may require 600 International Units (IUs).
  • People ages 71 and older may require as much as 800 IUs.

The IOM also recommended that no more than 4,000 IUs of vitamin D be taken per day.

To help ensure coordinated and safe care, people should discuss use of complementary and alternative medicine practices, including the use of dietary supplements, with their health care provider.

More information about using dietary supplements to help with diabetes is available from the NDIC at www.diabetes.niddk.nih.gov/dm/pubs/alternativetherapies/index.aspx.

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Physical Activity

Regular physical activity tackles several risk factors at once. Regular physical activity helps the body use insulin properly.

Regular physical activity also helps a person

  • lose weight
  • control blood glucose levels
  • control blood pressure
  • control cholesterol levels

People in the DPP who were physically active for 30 minutes a day, 5 days a week, reduced their risk of type 2 diabetes. Many chose brisk walking as their physical activity.

Most people should aim for at least 30 minutes of exercise most days of the week. For best results, people should do both aerobic activities, which use large muscle groups and make the heart beat faster, and muscle strengthening activities.

Aerobic activities include brisk walking, climbing stairs, swimming, dancing, and other activities that increase the heart rate.

Muscle strengthening activities include lifting weights and doing sit-ups or push-ups.

People who haven’t been physically active recently should talk with their health care provider about which activities are best for them and have a checkup before starting an exercise program.

Not Smoking

Those who smoke should quit. A health care provider can help people find ways to quit smoking. Studies show that people who get help have a better chance of quitting.

For more information about how to reverse insulin resistance and prediabetes with diet and increased physical activity, see the following National Diabetes Education Program publications at www.yourdiabetesinfo.org:

  • Get Real! You Don’t Have to Knock Yourself Out to Prevent Diabetes!
  • More Than 50 Ways to Prevent Diabetes
  • Small Steps. Big Rewards. Your Game Plan to Prevent Type 2 Diabetes.

Medication

The medication metformin is recommended for treatment of some individuals at very high risk of developing type 2 diabetes. In the DPP, metformin was shown to be most effective in preventing or delaying the development of type 2 diabetes in younger, heavier people with prediabetes. In general, metformin is recommend for those who are younger than age 60 and have

  • combined IGT and IFG
  • A1C above 6 percent
  • low HDL cholesterol
  • elevated triglycerides
  • a parent or sibling with diabetes
  • a BMI of at least 35

Metformin also lowers the risk of diabetes in women who have had gestational diabetes. People at high risk should ask their health care provider if they should take metformin to prevent type 2 diabetes.

Several medications have been shown to reduce type 2 diabetes risk to varying degrees, but the only medication recommended by the ADA for type 2 diabetes prevention is metformin. Other medications that have delayed diabetes have side effects or haven’t shown long-lasting benefits. No medication, including metformin, is approved by the U.S. Food and Drug Administration to treat insulin resistance or prediabetes or to prevent type 2 diabetes.

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Points to Remember

  • Insulin is a hormone that helps cells throughout the body absorb glucose and use it for energy. Insulin resistance is a condition in which the body produces insulin but does not use it effectively.
  • Insulin resistance increases the risk of developing type 2 diabetes and prediabetes.
  • The major contributors to insulin resistance are excess weight, especially around the waist, and physical inactivity.
  • Prediabetes is a condition in which blood glucose or A1C levels—which reflect average blood glucose levels—are higher than normal but not high enough for a diagnosis of diabetes.
  • The Diabetes Prevention Program (DPP) study and its follow-up study, the Diabetes Prevention Program Outcomes Study (DPPOS), confirmed 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.
  • By losing weight and being more physically active, people can reverse insulin resistance and prediabetes, thus preventing or delaying type 2 diabetes.
  • People with insulin resistance and prediabetes can decrease their risk for diabetes by eating a healthy diet and reaching and maintaining a healthy weight, increasing physical activity, not smoking, and taking medication.
  • The DPP showed the diabetes medication metformin to be most effective in preventing or delaying the development of type 2 diabetes in younger and heavier people with prediabetes and women who have had gestational diabetes.

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Hope through Research

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) conducts and supports research in insulin resistance, diabetes, glucose metabolism, and related conditions. Clinical trials related to diabetes include

  • Genetic Studies of Insulin and Diabetes, funded by the NIDDK under NIH clinical trial number NCT00001987
  • Exercise Training in Type 2 Diabetes and Hypertension, funded by the NIDDK under NIH clinical trial number NCT00212303
  • Diabetes and Heart Disease Risk in Blacks, funded by the NIDDK under NIH clinical trial number NCT00001853

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 about the NIDDK’s research on diabetes and related topics, see www.diabetes.niddk.nih.gov/diabetesresearch/dm_research.aspx.

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For More Information

American Association of Diabetes Educators
200 West Madison Street, Suite 800
Chicago, IL 60606
Phone: 1–800–338–3633 or 312–424–2426
Diabetes Educator Access Line: 1–800–TEAMUP4 (1–800–832–6874)
Fax: 312–424–2427
Email: aade@aadenet.org
Internet: www.diabeteseducator.orgleaving site icon

American Diabetes Association
1701 North Beauregard Street
Alexandria, VA 22311
Phone: 1–800–DIABETES (1–800–342–2383)
Email: AskADA@diabetes.org
Internet: www.diabetes.orgleaving site icon

National Heart, Lung, and Blood Institute Information Center
P.O. Box 30105
Bethesda, MD 20824–0105
Phone: 301–592–8573
TTY: 240–629–3255
Fax: 240–629–3246
Email: nhlbiinfo@nhlbi.nih.gov
Internet: www.nhlbi.nih.gov

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Acknowledgments

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.

You may also find additional information about this topic by visiting MedlinePlus at www.medlineplus.gov.

This publication may contain information about medications and, when taken as prescribed, the conditions they treat. 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 (1–888–463–6332) or visit www.fda.gov. Consult your health care provider 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.


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National Diabetes Education Program

1 Diabetes Way
Bethesda, MD 20814–9692
Phone: 1–888–693–NDEP (1–888–693–6337)
TTY: 1–866–569–1162
Fax: 703–738–4929
Email: ndep@mail.nih.gov
Internet: www.ndep.nih.gov
www.yourdiabetesinfo.org

The National Diabetes Education Program is a federally funded program sponsored by the U.S. Department of Health and Human Services’ National Institutes of Health and the Centers for Disease Control and Prevention and includes over 200 partners at the federal, state, and local levels, working together to reduce the morbidity and mortality associated with diabetes.

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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.

This publication is not copyrighted. The Clearinghouse encourages users of this publication to duplicate and distribute as many copies as desired.


NIH Publication No. 13–4893
November 2012

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Page last updated January 22, 2013


The National Diabetes Information Clearinghouse is a service of the National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health.

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

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