How do doctors determine if you have type 2 diabetes? The doctor has three different tests he can perform to see if your blood glucose levels fit into the range of diabetes or pre-diabetes. These include the fasting plasma glucose, the oral glucose tolerance test, and the random plasma glucose test. All but the last one will then diagnose diabetes and pre-diabetes. The last one will only diagnose diabetes. When you come into the doctor’s office with a list of symptoms, your doctor will likely recommend one of these three. Let’s look at each one and what the results may be.

The first type of test your doctor may perform to check for type 2 diabetes is the fasting plasma glucose or FPG. This health test is both convenient and also low priced. This makes it the first choice for many physicians to make an initial diagnosis. It may occassionally yield a wrong answer or a false negative. So many medical teams may use another test to then verify. With this test, the patient must fast for 8 hours before. Many doctors perform the test early in the morning before the patient eats breakfast. The test measures the glucose levels in milligrams per deciliter or mmol/L. With a reading of 99 mg/dl (5.5 mmol/l) or below, the patient is normal and does not have diabetes. If the reading is between 100 and 125 mg/dl (5.6 – 7.0 mmol/L), the patient likely has pre-diabetes. A reading over 125 mg/dl (7.0 mmol/l) now implies the person likely has Type 2 Diabetes. Your healthcare team will likely repeat the test if they need to verify the final result.

Another test performed is the oral glucose tolerance test or OGTT. It is definitely more sensitive or accurate than the FPG. It also requires an 8 hour fast. At the time of the test, the technician takes the plasma glucose level. Immediately after this, the person has a glass of water with 75 grams of glucose dissolved in it. Two hours later, the technician then takes a second plasma glucose level. The reading taken after the two hours is what is measured. If the blood glucose level is in the vicinity 139 mg/dl (7.7 mmol/l) or less, the person is then clear of Diabetes. If the reading is between, 140 and 199 mg/dl (7.7 -11 mmol/l), the patient has pre-diabetes. If the reading is over 200 mg/dl (11 mmol/l), the patient has diabetes.