<s>[INST] Which tests are used to diagnose diabetes and pre-diabetes? [/INST] There are three types of tests routinely performed to diagnose pre-diabetes and diabetes. 

Fasting Plasma Glucose Test (FPG) Just prior to having this test run, the patient must fast (nothing to eat or drink except water) for eight hours. The health care provider draws blood from the patient. Then the plasma (the fluid part of the blood) is combined with other substances to determine the amount of glucose in the plasma, as measured in mg/dL. The chart below contains the FPG test's blood glucose ranges for prediabetes and diabetes and describes what each diagnosis means.
HbA1C (A1C or glycosylated hemoglobin test) The A1C test can be used for the diagnosis of both prediabetes and diabetes. The average blood glucose for the past 2 to 3 months is measured with HbA1c. This test is more convenient because no fasting is required. An A1C of 5.7% to 6.4% means that there is a high risk for the development of diabetes and that the patient has pre-diabetes. Diabetes is diagnosed when the A1C is 6.5% or higher.
Oral Glucose Tolerance Test (OGTT) The test measures how well the body handles a standard amount of glucose. The health care provider draws the patient's blood before and two hours after the patient drinks a large, premeasured beverage containing glucose. Then, the doctor can compare the before-and-after glucose levels contained in the person's plasma to see how well the body processed the sugar. These levels are measured in mg/dL. The chart below contains the OGTT's blood glucose ranges for prediabetes and diabetes and describes what each diagnosis means. Source: HEMOCUE. Link: https://www.hemocue.com/en/health-areas/diabetes/what-is-diabetes-faq. Field: Endocrine. Disease: Diabetes </s>