Article # 78. Prediabetes

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.

 

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.

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.

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.