Diabetes & Prediabetes Tests
This fact sheet compares the following tests:
fasting plasma glucose (FPG) test
oral glucose tolerance test (OGTT)
random plasma glucose (RPG) test
Confirming Diagnosis of Type 2 Diabetes and Prediabetes
Diagnosis must be confirmed unless symptoms are present. Repeat the test using one of the following methods:
Repeat the same test on a different day—preferred.
If two different tests are used—e.g., FPG and A1C—and both indicate diabetes, consider the diagnosis confirmed.
If the two different tests are discordant, repeat the test that is above the diagnostic cut point.
If diagnosis cannot be confirmed using the results of two tests, but at least one test indicates high risk, health care providers may wish to follow the patient closely and retest in 3 to 6 months.1
Interpreting Laboratory Results
When interpreting laboratory results health care providers should
consider that all laboratory test results represent a range, rather than an exact number2
be informed about the A1C assay methods used by their laboratory2
send blood samples for diagnosis to a laboratory that uses an NGSP-certified method for A1C analysis to ensure the results are standardized3
consider the possibility of interference in the A1C test when a result is above 15% or is at odds with other diabetes test results1
consider each patient’s profile, including risk factors and history, and individualize diagnosis and treatment decisions in discussion with the patient1
Comparing Diabetes Blood Tests‡
View the content below as a table in the PDF Version (460 KB) .
Screening and di Continue reading