Screening Tests

Random Plasma Glucose Test—As part of your routine physical exam, your doctor may draw some blood to check your liver, kidney, and endocrine functions, including blood glucose. This blood is taken any time of day, without regard to when you have last eaten. A measure of 200 milligrams per deciliter (mg/dl) [11.1 mmol/L] may indicate diabetes. In this case, your doctor will do further testing to determine if you have diabetes.

Health Fair Screening—Blood glucose testing is often done at health fairs as well. Here, you will need to give only a few drops of blood from your fingertip, and you'll have results within a few minutes. If the results indicate that your blood glucose level is high, you should see your doctor for further testing.

See the diagnosis page for a description of the further testing your doctor will do.

Screening Guidelines

It is estimated that 16 million Americans have prediabetes, which is also called impaired glucose tolerance. This condition is characterized by high blood glucose levels that aren't high enough to be diagnosed as diabetes. However, the condition often progresses to type 2 diabetes.

In order to detect prediabetes and take steps to prevent its progression to type 2 diabetes, the American Diabetes Association and the US Preventive Services Task Force recommend the following:

American Diabetes Association Recommendations:

• Testing in all overweight adults with BMI greater than 25 and have the following risk factors:
  • Physical inactivity
  • First-degree relative with diabetes
  • High-risk ethnic groups
  • Women with gestational diabetes or have delivered heavy babies weighing more than 9 pounds (4.1 kg)
  • High blood pressure
  • HDL cholesterol level less than 35 mg/dl or triglyceride level greater than 250 mg/dl
  • Polycystic ovarian syndrome
  • Glycose intolerance
  • Conditions associated with insulin resistance
  • History of cardiovascular disease
• Screen those over age 45 years in the absence of the above conditions.
• If screen results are normal, repeat screen at least once every 3 years.

USPSTF Recommendations:

• Screen those with sustained blood pressure over 135/80 mm Hg.
• No need to screen those with blood pressure below 135/80 mm Hg.

Screening for diabetes in these cases is part of an overall approach to reduce the risk of heart disease in people with these risk factors.