The glucose tolerance test is a medical test in which glucose is given and blood samples taken afterward to determine how quickly it is cleared from the blood. The test is usually used to test for diabetes, insulin resistance, impaired beta cell function, and sometimes reactive hypoglycemia and acromegaly, or rarer disorders of carbohydrate metabolism. In the most commonly performed version of the test, an oral glucose tolerance test (OGTT), a standard dose of glucose is ingested by mouth and glucose blood levels are checked right after ingestion and then two hours later. 

The fasting insulin test is a blood test that measures the level of insulin in your blood after you have fasted (not eaten or drunk anything except water) for at least 8 hours. Insulin is a hormone produced by the pancreas that helps regulate blood sugar levels. The fasting insulin test is often used to help diagnose conditions such as insulin resistance, prediabetes, and type 2 diabetes. It may also be ordered to monitor the effectiveness of treatment for these conditions. The test is usually done in the morning, after an overnight fast. The test results will be reported in units of insulin per liter of blood (U/L). It is important to note that the interpretation of a fasting insulin test may vary depending on the individual's medical history and other factors. A healthcare provider should be consulted to interpret the test results correctly.