Your doctor will perform one of the standard meas- urements for the diagnosis of diabetes approved by the accepted authoritative body in whichever part of the world you live. In the United States, this is gen- erally set by the American Diabetes Association (ADA) and is accepted by most practitioners, insur- ers, and health providers as valid. The most current ADA criteria for the diagnosis of diabetes are shown in Table 1 (see Question 9). Your doctor may or may not ask you to fast prior to measuring the blood glu- cose or he or she may perform a standard 2-hour test known as the oral glucose tolerance test. Unless they are clearly and indisputably abnormal, or accompa- nied by typical symptoms of diabetes (discussed in Question 4), the results should be confirmed on a different day, since the diagnosis of diabetes carries many implications and necessitates lifelong monitor- ing and treatment. Very soon, the test that measures the average blood glucose over the past 3 months (the Hemoglobin A1c or HbA1c test) is also likely to become a standard test for detection and diagnosis of diabetes.
Different diagnostic procedures are used for pregnant women, most of whom should be screened for the presence of diabetes of pregnancy (“gestational dia- betes”) during the 24th to 28th week of pregnancy or earlier if they are at high risk or had diabetes in a previous pregnancy. This involves an initial 1-hour screening test for which fasting is not required. If the screening test is positive, it is followed by a more detailed 3-hour test for which prior fasting is necessary.