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Diagnosis of Diabetes and Prediabetes

On this page:

What is diabetes?

Diabetes is a complex group of diseases with a variety of causes. People with diabetes have high blood glucose, also called high blood sugar or hyperglycemia.

Diabetes is a disorder of 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, a form of sugar that enters the bloodstream. With the help of the hormone insulin, cells throughout the body absorb glucose and use it for energy. Insulin is made in the pancreas, an organ located behind the stomach. As the blood glucose level rises after a meal, the pancreas is triggered to release insulin. Within the pancreas, clusters of cells called islets contain beta cells, which make the insulin and release it into the blood.

Diabetes develops when the body doesn’t make enough insulin or is not able to use insulin effectively, or both. As a result, glucose builds up in the blood instead of being absorbed by cells in the body. The body’s cells are then starved of energy despite high blood glucose levels.

Over time, high blood glucose damages nerves and blood vessels, leading to complications such as heart disease, stroke, kidney disease, blindness, dental disease, and amputations. Other complications of diabetes may include increased susceptibility to other diseases, loss of mobility with aging, depression, and pregnancy problems.

Drawing of a torso showing the liver, pancreas, and a pancreatic islet showing beta cells.
Islets within the pancreas contain beta cells, which make insulin and release it into the blood.

Main Types of Diabetes

The three main types of diabetes are type 1, type 2, and gestational diabetes:

  • Type 1 diabetes, formerly called juvenile diabetes, is usually first diagnosed in children, teenagers, and young adults. In this type of diabetes, the beta cells of the pancreas no longer make insulin because the body’s immune system has attacked and destroyed them.
  • Type 2 diabetes, formerly called adult-onset diabetes, is the most common type of diabetes. About 95 percent of people with diabetes have type 2.1 People can develop type 2 diabetes at any age, even during childhood, but this type of diabetes is most often associated with older age. Type 2 diabetes is also associated with excess weight, physical inactivity, family history of diabetes, previous history of gestational diabetes, and certain ethnicities.

    Type 2 diabetes usually begins with insulin resistance, a condition linked to excess weight in which muscle, liver, and fat cells do not use insulin properly. As a result, the body needs more insulin to help glucose enter cells to be used for energy. At first, the pancreas keeps up with the added demand by producing more insulin. But in time, the pancreas loses its ability to produce enough insulin in response to meals, and blood glucose levels rise.

  • Gestational diabetes is a type of diabetes that develops only during pregnancy. Gestational diabetes affects 2 to 10 percent of all pregnancies.1

    The hormones produced during pregnancy increase the amount of insulin needed to control blood glucose levels. If the body can’t meet this increased need for insulin, women can develop gestational diabetes during the late stages of pregnancy.

    Although this type of diabetes usually goes away after the baby is born, women who have had gestational diabetes are more likely to develop type 2 diabetes later in life. Research has shown that lifestyle changes and the diabetes medication, metformin, can reduce or delay the risk of type 2 diabetes in these women. Babies born to mothers who had gestational diabetes are also more likely to develop obesity and type 2 diabetes as they grow up.

    More information about gestational diabetes is available in the booklet What I need to know about Gestational Diabetes, available online from the National Diabetes Information Clearinghouse (NDIC) at www.diabetes.niddk.nih.gov or by calling 1–800–860–8747.

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, 2011.

Other Types of Diabetes

Many other types of diabetes exist, and a person can exhibit characteristics of more than one type. For example, in latent autoimmune diabetes in adults, people show signs of both type 1 and type 2 diabetes. Other types of diabetes include those caused by genetic defects, diseases of the pancreas, excess amounts of certain hormones resulting from some medical conditions, medications that reduce insulin action, chemicals that destroy beta cells, infections, rare autoimmune disorders, and genetic syndromes associated with diabetes.

For more information about other types of diabetes, see the NDIC fact sheet Causes of Diabetes, available at www.diabetes.niddk.nih.gov or by calling 1–800–860–8747.

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What is prediabetes?

Prediabetes is when blood glucose levels are higher than normal but not high enough for a diagnosis of diabetes. Prediabetes means a person is at increased risk for developing type 2 diabetes, as well as for heart disease and stroke. Many people with prediabetes develop type 2 diabetes within 10 years.

However, modest weight loss and moderate physical activity can help people with prediabetes delay or prevent type 2 diabetes.

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

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How are diabetes and prediabetes diagnosed?

Blood tests are used to diagnosis diabetes and prediabetes because early in the disease type 2 diabetes may have no symptoms. All diabetes 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.

Testing enables health care providers to find and treat diabetes before complications occur and to find and treat prediabetes, which can delay or prevent type 2 diabetes from developing.

Any one of the following tests can be used for diagnosis:*

  • an A1C test, also called the hemoglobin A1c, HbA1c, or glycohemoglobin test
  • a fasting plasma glucose (FPG) test
  • an oral glucose tolerance test (OGTT)

*Not all tests are recommended for diagnosing all types of diabetes. See the individual test descriptions for details.

Another blood test, the random plasma glucose (RPG) test, is sometimes used to diagnose diabetes during a regular health checkup. If the RPG measures 200 micrograms per deciliter or above, and the individual also shows symptoms of diabetes, then a health care provider may diagnose diabetes.

Symptoms of diabetes include

  • increased urination
  • increased thirst
  • unexplained weight loss

Other symptoms can include fatigue, blurred vision, increased hunger, and sores that do not heal.

Any test used to diagnose diabetes requires confirmation with a second measurement unless clear symptoms of diabetes exist.

The following table provides the blood test levels for diagnosis of diabetes for nonpregnant adults and diagnosis of prediabetes.


Source: Adapted from American Diabetes Association. Standards of medical care in diabetes—2012. Diabetes Care. 2012;35(Supp 1):S12, table 2.

A1C Test

The A1C test is used to detect type 2 diabetes and prediabetes but is not recommended for diagnosis of type 1 diabetes or gestational diabetes. The A1C test is a blood test that reflects the average of a person’s blood glucose levels over the past 3 months and does not show daily fluctuations. The A1C test is more convenient for patients than the traditional glucose tests because it does not require fasting and can be performed at any time of the day.

The A1C test result is reported as a percentage. The higher the percentage, the higher a person’s blood glucose levels have been. A normal A1C level is below 5.7 percent.

An A1C of 5.7 to 6.4 percent indicates prediabetes. People diagnosed with prediabetes may be retested in 1 year. People with an A1C below 5.7 percent maystill be at risk for diabetes, depending on the presence of other characteristics that put them at risk, also known as risk factors. 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.

Laboratory analysis. When the A1C test is used for diagnosis, the blood sample must be sent to a laboratory using a method that is certified by the NGSP to ensure the results are standardized. Blood samples analyzed in a health care provider’s office, known as point-of-care tests, are not standardized for diagnosing diabetes.

Abnormal results. The A1C test can be unreliable for diagnosing or monitoring diabetes in people with certain conditions 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.

However, not all of the A1C tests are unreliable for people with these diseases. The NGSP provides information about which A1C tests are appropriate to use for specific types of interference and details on any problems with the A1C test at www.ngsp.org Exit Disclaimer image.

False A1C test results may also occur in people with other problems that affect their blood or hemoglobin such as chronic kidney disease, liver disease, or anemia.

More information about limitations of the A1C test and different forms of sickle cell anemia is available in the NDIC booklet For People of African, Mediterranean, or Southeast Asian Heritage: Important Information about Diabetes Blood Tests, available at www.diabetes.niddk.nih.gov or by calling 1–800–860–8747.

Changes in Diagnostic Testing

In the past, the A1C test was used to monitor blood glucose levels but not for diagnosis. The A1C test has now been standardized, and in 2009, an international expert committee recommended it be used for diagnosis of type 2 diabetes and prediabetes.2

More information about the A1C test is available in the NDIC fact sheet The A1C Test and Diabetes, available at www.diabetes.niddk.nih.gov or by calling 1–800–860–8747.

2The International Expert Committee. International Expert Committee report on the role of the A1C assay in the diagnosis of diabetes. Diabetes Care. 2009;32(7):1327–1334.

Fasting Plasma Glucose Test

The FPG test is used to detect diabetes and prediabetes. The FPG test has been the most common test used for diagnosing diabetes because it is more convenient than the OGTT and less expensive. The FPG test measures blood glucose in a person who has fasted for at least 8 hours and is most reliable when given in the morning.

People with a fasting glucose level of 100 to 125 mg/dL have impaired fasting glucose (IFG), or prediabetes. A level of 126 mg/dL or above, confirmed by repeating the test on another day, means a person has diabetes.

Oral Glucose Tolerance Test

The OGTT can be used to diagnose diabetes, prediabetes, and gestational diabetes. Research has shown that the OGTT is more sensitive than the FPG test, but it is less convenient to administer. When used to test for diabetes or prediabetes, the OGTT measures blood glucose after a person fasts for at least 8 hours and 2 hours after the person drinks a liquid containing 75 grams of glucose dissolved in water.

If the 2-hour blood glucose level is between 140 and 199 mg/dL, the person has a type of prediabetes called impaired glucose tolerance (IGT). If confirmed by a second test, a 2-hour glucose level of 200 mg/dL or above means a person has diabetes.

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Are diabetes blood test results always accurate?

All laboratory test results can vary from day to day and from test to test. Results can vary

  • within the person being tested. A person’s blood glucose levels normally move up and down depending on meals, exercise, sickness, and stress.
  • between different tests. Each test measures blood glucose levels in a different way.
  • within the same test. Even when the same blood sample is repeatedly measured in the same laboratory, the results may vary due to small changes in temperature, equipment, or sample handling.

Although all these tests can be used to indicate diabetes, in some people one test will indicate a diagnosis of 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 take all these variations into account when considering test results and repeat laboratory tests for confirmation. 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.

More information about variation among diabetes blood test results is available in the NDIC publication The A1C Test and Diabetes, available at www.diabetes.niddk.nih.gov or by calling 1–800–860–8747.

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Diagnosis of Gestational Diabetes

Health care providers test for gestational diabetes using the OGTT. Women may be tested during their first visit to the health care provider after becoming pregnant or between 24 to 28 weeks of pregnancy depending on their risk factors and symptoms. Women found to have diabetes at the first visit to the health care provider after becoming pregnant may be diagnosed with type 2 diabetes.

Defining Safe Blood Glucose Levels for Pregnancy

Many studies have shown that gestational diabetes can cause complications for the mother and baby. An international, multicenter study, the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study, showed that the higher a pregnant woman’s blood glucose is, the higher her risk of pregnancy complications. The HAPO researchers found that pregnancy complications can occur at blood glucose levels that were once considered to be normal.

Based on the results of the HAPO study, new guidelines for diagnosis of gestational diabetes were recommended by the International Association of the Diabetes and Pregnancy Study Groups in 2011. So far, the new guidelines have been adopted by the American Diabetes Association (ADA)3 but not by the American College of Obstetricians and Gynecologists (ACOG)4 or other medical organizations. Researchers estimate these new guidelines, if widely adopted, will increase the proportion of pregnant women diagnosed with gestational diabetes to nearly 18 percent.5

Both ADA and ACOG guidelines for using the OGTT in diagnosing gestational diabetes are shown in the following tables.

3American Diabetes Association. Standards of medical care in diabetes—2012. Diabetes Care. 2012;35(Supp 1):S11–S63.

4Committee on Obstetric Practice, Committee Opinion No. 504, American College of Obstetricians and Gynecologists. Screening and diagnosis of gestational diabetes mellitus. Obstetrics and Gynecology. 2011;118:751–753.

5International Association of Diabetes and Pregnancy Study Groups Consensus Panel. International association of diabetes and pregnancy study groups recommendations on the diagnosis and classification of hyperglycemia in pregnancy. Diabetes Care. 2010;33:676–682.

Recommendations for Testing Pregnant Women for Diabetes

Time of testing ACOG ADA
At first visit during pregnancy No recommendation Test women with risk factors for diabetes using standard testing for diagnosis of type 2 diabetes.

Women found to have diabetes at this time should be diagnosed with type 2 diabetes, not gestational diabetes.
At 24 to 28 weeks of pregnancy Test women for diabetes based on their history, risk factors, or a 50-gram, 1-hour, nonfasting, glucose challenge test—a modified OGTT.

If score is 130–140 mg/dL, test again with fasting, 100-gram, 3-hour OGTT.*
Test all women for diabetes who are not already diagnosed, using a fasting, 75-gram, 2-hour OGTT.*

*See “OGTT Levels for Diagnosis of Gestational Diabetes” for blood glucose levels.

OGTT Levels for Diagnosis of Gestational Diabetes

Time of Sample Collection ACOG Levels**,4 (mg/dL) ADA Levels3(mg/dL)
100-gram Glucose Drink 75-gram Glucose Drink
Fasting, before drinking glucose 95 or above 92 or above
1 hour after drinking glucose 180 or above 180 or above
2 hours after drinking glucose 155 or above 153 or above
3 hours after drinking glucose 140 or above Not used
Requirements for Diagnosis TWO or more of the above levels must be met ONE or more of the above levels must be met

**Carpenter and Coustan Conversion, some labs use different numbers.

More information about treating gestational diabetes is available in the NDIC publication What I need to know about Gestational Diabetes, available at www.diabetes.niddk.nih.gov or by calling 1–800–860–8747.

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Who should be tested for diabetes and prediabetes?

Adults, pregnant women, children, and teens should be tested for diabetes and prediabetes according to their risk factors.

Adults

Anyone age 45 or older should consider getting tested for diabetes or prediabetes. Testing is strongly recommended for people older than age 45 who are overweight or obese. People younger than 45 should consider testing if they are overweight or obese*** and have one or more of the following risk factors:

  • physical inactivity
  • parent, brother, or sister with diabetes
  • family background that is African American, Alaska Native, American Indian, Asian American, Hispanic/Latino, or Pacific Islander American
  • history of giving birth to at least one baby weighing more than 9 pounds
  • history of gestational diabetes
  • high blood pressure—140/90 mmHg or higher—or being diagnosed with high blood pressure
  • high-density lipoprotein, or HDL, cholesterol—“good” cholesterol—level below 35 mg/dL or a triglyceride level above 250 mg/dL
  • polycystic ovary syndrome, also called PCOS
  • prediabetes—an A1C level of 5.7 to 6.4 percent; an FPG test result of 100–125 mg/dL, indicating IFG; or a 2-hour OGTT result of 140–199 mg/dL, indicating IGT
  • acanthosis nigricans, a condition associated with insulin resistance and characterized by a dark, velvety rash around the neck or armpits
  • history of cardiovascular disease—disease affecting the heart and blood vessels

***The “Body Mass Index” chart (PDF, 70 KB) * can be used to find out whether someone is normal weight, overweight, or obese.

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 body mass index (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: www.cdc.gov

If results of testing 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. People whose test results indicate they have prediabetes may be tested again in 1 year and should take steps to prevent or delay type 2 diabetes.

Pregnant Women

All pregnant women with risk factors for type 2 diabetes should be tested using standard diabetes blood tests during their first visit to the health care provider during pregnancy to see if they had undiagnosed diabetes before becoming pregnant. After that, pregnant women should be tested for gestational diabetes between 24 and 28 weeks of their pregnancy using the OGTT.

Women who develop gestational diabetes should also have follow-up testing 6 to 12 weeks after the baby is born to find out if they have type 2 diabetes or prediabetes. If results of testing are normal, testing should be repeated at least every 3 years. Blood glucose tests, rather than the A1C test, should be used for testing within 12 weeks of delivery.

Children and Teens

Type 2 diabetes has become increasingly common in children and teens. Children are at high risk for developing type 2 diabetes and should be tested if they are

  • overweight or obese and have other risk factors, such as a family history of diabetes
  • older than age 10 or have already gone through puberty

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Body Mass Index (BMI)

Body mass index is a measurement of body weight relative to height for adults age 20 or older. To use the chart

  • find the person’s height in the left-hand column
  • move across the row to find the number closest to the person’s weight
  • find 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, or obese. People who are overweight or obese should consider talking with a health care provider about ways to lose weight and reduce the risk of diabetes.

The BMI has certain limitations. The BMI 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.

The BMI for children and teens must be determined based on age, height, weight, and sex. The Centers for Disease Control and Prevention (CDC) has information about BMI in children and teens, including a BMI calculator, 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



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

 

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

For a printer-friendly version of this table, use the pdf. (PDF, 70 KB)*

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What steps can delay or prevent type 2 diabetes?

A major research study, the Diabetes Prevention Program (DPP), proved that people with prediabetes were able to sharply reduce their risk of developing diabetes during the study by losing 5 to 7 percent of their body weight through dietary changes and increased physical activity.

Study participants followed a low-fat, low-calorie diet and engaged in regular physical activity, such as walking briskly five times a week for 30 minutes. These strategies worked well for both men and women in all racial and ethnic groups, but were especially effective for participants age 60 and older. A follow-up study, the Diabetes Prevention Program Outcomes Study (DPPOS), showed losing weight and being physically active provide lasting results. Ten years after the DPP, modest weight loss delayed onset of type 2 diabetes by an average of 4 years.

The diabetes medication metformin also lowers the risk of type 2 diabetes in people with prediabetes, especially those who are younger and heavier and women who have had gestational diabetes. The DPPOS showed that metformin delayed type 2 diabetes by 2 years. People at high risk should ask their health care provider if they should take metformin to prevent type 2 diabetes. Metformin is a medication that makes insulin work better and can reduce the risk of type 2 diabetes.

More information about insulin resistance, the DPP, or how to lower risk for type 2 diabetes is available in the following NDIC publications:

  • Am I at Risk for Type 2 Diabetes?
  • Diabetes Prevention Program (DPP)
  • Insulin Resistance and Prediabetes

These publications are available at www.diabetes.niddk.nih.gov or by calling 1–800–860–8747. Additional information about the DPP, funded under NIH clinical trial number NCT00004992, and the DPPOS, funded under NIH clinical trial number NCT00038727, can be found at www.bsc.gwu.edu/dpp Exit Disclaimer image.

As part of its Small Steps, Big Rewards campaign, the National Diabetes Education Program (NDEP) offers several booklets about preventing type 2 diabetes, including information about setting goals, tracking progress, implementing a walking program, and finding additional resources. These materials are available at www.ndep.nih.gov or by calling the NDEP at 1–888–693–NDEP (1–888–693–6337).

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How is diabetes managed?

People can manage their diabetes with meal planning, physical activity, and if needed, medications. Additional information about taking care of type 1 or type 2 diabetes is available in the publications

  • What I need to know about Diabetes Medicines
  • What I need to know about Eating and Diabetes
  • Your Guide to Diabetes: Type 1 and Type 2

These NDIC publications are available at www.diabetes.niddk.nih.gov or by calling 1–800–860–8747.

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Points to Remember

  • Tests used for diagnosing diabetes and prediabetes include the A1C test—for type 2 diabetes and prediabetes—the fasting plasma glucose (FPG) test, and the oral glucose tolerance test (OGTT). Another blood test, the random plasma glucose (RPG) test, is sometimes used to diagnose diabetes when symptoms are present during a regular health checkup.
  • Anyone age 45 or older should consider getting tested for diabetes or prediabetes. People younger than 45 should consider testing if they are overweight or obese and have one or more additional risk factors for diabetes.
  • If results of testing 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.
  • People whose test results indicate they have prediabetes may be tested again in 1 year and should take steps to prevent or delay type 2 diabetes.
  • Many people with prediabetes develop type 2 diabetes within 10 years.
  • Modest weight loss and moderate physical activity can help people with prediabetes delay or prevent type 2 diabetes.

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Hope through Research

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) conducts and supports research related to the causes, treatment, and prevention of diabetes. The NIDDK conducts research in its own laboratories and supports a great deal of basic and clinical research in medical centers and hospitals throughout the United States. The NIDDK also gathers and analyzes statistics about diabetes. Other Institutes at the NIH conduct and support research on diabetes-related eye diseases, heart and vascular complications, autoimmunity, pregnancy, and dental problems.

The NIDDK also works collaboratively on diagnostic issues with other Government agencies that sponsor diabetes programs such as the CDC, the Indian Health Service, the Health Resources and Services Administration, the U.S. Department of Veterans Affairs, and the U.S. Department of Defense.

Clinical trials related to diabetes include

  • Molecular and Clinical Profile of Diabetes Mellitus and Its Complications, funded by the NIDDK under NIH clinical trial number NCT01105858
  • 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.

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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.org Exit Disclaimer image

American Diabetes Association
1701 North Beauregard Street
Alexandria, VA 22311
Phone: 1–800–DIABETES (1–800–342–2383)
Fax: 703–549–6995
Email: AskADA@diabetes.org
Internet: www.diabetes.org Exit Disclaimer image

JDRF
26 Broadway, 14th Floor
New York, NY 10004
Phone: 1–800–533–CURE (1–800–533–2873)
Fax: 212–785–9595
Email: info@jdrf.org
Internet: www.jdrf.org Exit Disclaimer image

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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 David Harlan, M.D., NIDDK.

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.

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.

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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. 12–4642
July 2012

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Page last updated April 9, 2014


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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