Prediabetes is a condition where blood glucose levels are higher than normal, but not high enough to be called diabetes. It is estimated that 79 million adults aged 20 and older have prediabetes.  


Studies have shown that by losing weight and increasing physical activity people can prevent or delay prediabetes from progressing to diabetes.  


About 1.9 million people ages 20 or older were diagnosed with diabetes.


25.8 million Americans have diabetes — 8.3 percent of the U.S. population. Of these, 7 million do not know they have the disease.

The number of people diagnosed with diabetes has risen from 1.5 million in 1958 to 18.8 million in 2010, an increase of epidemic proportions.

Learn more.


There are no symptoms of prediabetes, most people find out about prediabetes when they get tested for diabetes. People with prediabetes may have some of the problems from diabetes already. You may have it and not aware of it.


The following information provides the blood test levels for diagnosis of diabetes and diagnosis of prediabetes.


A1C Test



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. Prediabetes  treatments can delay or prevent type 2 diabetes from developing.

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


  • A1C test, also called the hemoglobin A1c test

  • Fasting plasma glucose (FPG) test

  • Oral glucose tolerance test (OGTT)


A blood test, Random Plasma Glucose (RPG) test, is sometimes used to diagnose severe 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.



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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