There are several tests that are done to determine if someone has diabetes. The most commonly used and preferred method is the Fasting Plasma Glucose test. The patient either fasts overnight or for eight hours. After this, a blood sample is taken and then analyzed for glucose. If the levels are above the nationally prescribed norm, the patient has diabetes.
There are other tests as well. Some of them require fasting, and some of them work in conjunction with other tests.
Impaired Fasting Glucose: This is a relatively new test. A sample of blood is taken and if glucose levels read higher than the norm but lower than diabetic range, the patient's body is slow to utilize insulin. Treatment should be discussed with a physician to see if diet change and weight loss can prevent full-blown diabetes.
Oral Glucose Tolerance: This tests consists of having the patient fast for at least eight hours. They also may not smoke. Two hours after drinking a liquid high in carbohydrates, blood samples will be taken every half hour up to a maximum of three hours. If the patient consistently shows elevated glucose levels, there is a positive diagnosis.
Random Blood Glucose: This one is partnered with either an oral glucose, fasting blood plasma or another random blood glucose test. Glucose levels are tested after eating and drinking. If the results are 200mg/dl (American measurement) or 11mmol/l (Canadian measurement), another one of the tests are performed to confirm diabetes.
Glucose Challenge: This test is performed on expectant mothers to see if they have gestational diabetes. Women of African American, Pacific Islander, Hispanic, Asian or Native American/Canadian decent and those who are overweight or have diabetes in their family are more likely to be tested. The glucose challenge is usually performed between the sixth and seventh month of pregnancy. A blood test is taken after the patient drinks liquid glucose. If the results are above the prescribed national norm, an oral glucose tolerance may be performed to confirm gestational diabetes.