Criteria for the diagnosis of diabetes:
All of these tests identify people with diabetes. However, the number of people that these tests identify and their characteristics vary between the 3 tests. For example, A1c varies by race/ethnicity independent of blood glucose levels. The implications of demographic differences in estimates of undiagnosed diabetes when using different laboratory tests are not known. Research is ongoing to ascertain the best use of laboratory blood tests to detect people who may have diabetes and to improve the understanding of who has diabetes (http://www.ngsp.org/CAC2009.asp).