Glucose is the primary blood sugar used by cells to make energy. Because glucose is so important to your cells, the body regulates it in many different ways. The one most commonly understood involves insulin, a hormone secreted by the pancreas that delivers glucose to cells throughout the body.

When you eat a meal, the pancreas responds by releasing insulin to transport the glucose into the cells. As long as receptors on the cell walls remain sensitive to insulin, the channeling of glucose out of the bloodstream occurs relatively quickly and without excessive insulin production.

Sometimes, however, the cells become resistant to insulin’s effects. When this happens, the pancreas pumps out ever-greater amounts of insulin in an attempt to force the glucose into the cells. This effort is only partially effective in most instances, and may result in higher blood glucose levels. Blood glucose levels that remain high over time can damage your eyes, kidneys, nerves, and blood vessels.

Your results will typically display one of the following common patterns, which can be useful information in determining how your body responds to consuming glucose:

This test can be used by your doctor to help diagnose diabetes and/or pre-diabetes.

How to prepare for this test:

• Eat a regular diet that includes carbohydrates daily for three days prior to the test.
• Fast for at least 8 hours but not more than 14 hours the night before the test (make sure you drink water in order not to get dehydrated)
• Take all medications as prescribed by your physician but do not take your supplements the morning of the blood draw.

What can I expect when I get to the lab?

A total of 4 blood glucose and 4 insulin specimens will be drawn as follows:

• A fasting glucose and insulin level will be drawn.
• A drink containing 75 grams of glucose will be given to you to drink.
• 3 additional glucose and insulin levels will be drawn at 1 hour, 2 hours and 3 hours after the drink has been administered. (Some labs will draw at 1/2 hour, 1 hour and 2 hours. Both timings provide valuable information but you will want to request the timing you prefer).
• You will need to remain at the draw facility and seated throughout the entire test. Please bring a book or other quiet activity to keep yourself occupied while you are waiting.