Your doctor will use blood tests to diagnose diabetes. One test requires that you not eat or drink for at least eight hours beforehand, but other tests do not. Ask your doctor what you should do.

Certain medications can interfere with blood glucose levels. These include steroids, some antidepressants, water pills, epinephrine, estrogen, birth control pills, lithium, some seizure medications, drugs containing aspirin and over-the-counter pain relievers. Make a list of all medications that you take and ask your doctor whether you need to stop taking any of them before your diabetes blood test.

Find out about your family's health history so you can tell your doctor whether anyone in your family has had diabetes.

Make a list of your symptoms. Include whether you've had any recent stress in your life. Stress can raise blood glucose levels.