Diagnosing Prediabetes

Who is at risk for prediabetes, and what are the tests for screening?

doctor and patient talk prediabetes

To protect yourself from the serious health complications associated with prediabetes, it is important to know the risk factors and get your recommended screenings. Prediabetes often has no symptoms. You can take this preliminary screening test from the American Diabetes Association. You can also talk to your healthcare providers about these simple blood tests for screening:

1. A1c test. This test, also referred to as the hemoglobin A1c, HbA1c, or glycohemoglobin test, reflects an average of blood glucose levels from the past three months.

  • An A1c of 5.7 to 6.4% indicates prediabetes.
  • Type 2 diabetes is diagnosed at 6.5% or above.

2. Fasting plasma glucose (FPG) test. This test measures the blood glucose level in an individual who has not eaten anything for at least eight hours.

  • A fasting glucose level between 100 and 125 mg/dl indicates prediabetes.
  • Type 2 diabetes is diagnosed at 126 mg/dl or above.

3. Oral glucose tolerance (OGTT) test. This test measures the blood glucose level in an individual who has not eaten anything for at least eight hours, and two hours after he or she drinks a dose of glucose administered by a healthcare provider.

  • A blood glucose level between 140 and 199 mg/dl indicates prediabetes.
  • Type 2 diabetes is diagnosed at 200 mg/dl or above.

The A1c, FPG, and OGTT tests all involve drawing blood and sending the sample to a lab for accurate analysis. Your healthcare provider might choose to use a combination of these diagnostic tests based on your personal health history and risk factors. They may also repeat tests to confirm the results.

If your test results indicate a prediabetes diagnosis, it is recommended that you get tested again in one year, and incorporate various lifestyle changes to reduce your risk of developing type 2 diabetes and other health complications.

Signs and Symptoms

Although prediabetes frequently has no symptoms, a condition called acanthosis nigricans may be present in severe cases. This condition is characterized by dark patches of skin located on the back of the neck, elbows, knees, knuckles, or armpits.1 Changes in vision may also be present as a symptom of prediabetes.2

Risk Factors

Whether or not you are experiencing the symptoms mentioned earlier, you may be at increased risk for prediabetes if you:1,3

  • are age 45 or older,
  • are overweight,
  • have a family history of prediabetes or type 2 diabetes,
  • are African American, Alaska Native, Hispanic/Latino, or Pacific Islander American,
  • have hypertension (high blood pressure) or high cholesterol,
  • participate in physical activity fewer than three times per week,
  • have had gestational diabetes (diabetes while pregnant) or have given birth to a baby weighing more than 9 pounds,
  • have polycystic ovary syndrome (PCOS),
  • have a history of cardiovascular disease.

Importance of Screenings

Prediabetes should be taken seriously. It has been shown to lead to not only type 2 diabetes, but also a number of conditions impacting the entire body, from heart disease and stroke, to blindness, kidney failure, and nerve damage.

Understanding your risk and getting screened for an early diagnosis, in addition to making healthy lifestyle changes, can help delay and even prevent getting type 2 diabetes—it may even reverse prediabetes.

Check with your health insurer about coverage for diabetes screening. Medicare Part B (Medical Insurance) covers two diabetes screenings per year for those with certain risk factors. You may be eligible to receive these lab tests at no cost to you if you have any of the following risk factors:4

  • High blood pressure (hypertension)
  • Obesity
  • A history of abnormal cholesterol and triglyceride levels (dyslipidemia)
  • A history of high blood sugar (blood glucose)

Additionally, Part B also covers these tests if two or more of the following risk factors apply to you:4

  • Age 65 or older
  • Overweight
  • Family history of diabetes
  • History of gestational diabetes (diabetes while pregnant) or birthing a baby weighing more than 9 pounds
Updated on: July 11, 2016
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