Three tests can be used to find out if you have prediabetes. They are the fasting plasma glucose test (FPG), the oral glucose tolerance test (OGTT), and the hemoglobin A1C (A1C). The FPG is done after you go without food (fast) for 8 hours. A normal fasting blood sugar level is less than 100 mg/dL. If you have the FPG test, prediabetes is a blood sugar level of 100 mg/dL to 125 mg/dL. Diabetes is a fasting blood sugar level of 126 mg/dL or greater on 2 or more separate occasions. The OGTT is done after 8 hours of fasting and 2 hours after you drink a sweet beverage. If you have the OGTT, prediabetes is a blood sugar level of 140 mg/dL to 199 mg/dL, 2 hours after the drink. Diabetes is a blood sugar level of 200 mg/dL or greater. The A1C is a blood test. It measures your average glucose level in your blood over a period of 3 months. You don’t need to fast before the blood test is done. Your healthcare provider may decide that you have prediabetes if your A1C result is between 5.7% and 6.4%, depending on the lab running the test. An A1C of 6.5% or higher can be used to diagnose diabetes.

The actual time span can vary, based on how physically active you are. If you are overweight, you can actually head off diabetes by losing weight, says the American Diabetes Association (ADA). If you lose 5% to 10% of your body weight and begin exercising for 30 minutes every day, you can greatly reduce your risk of developing type 2 diabetes. Be sure to check with your healthcare provider before starting an exercise program. If you smoke, quit smoking.

People with prediabetes are more likely to develop heart disease than those who have normal blood sugar levels, according to the American Heart Association. A person with diabetes is 2 to 4 times more likely to die from heart disease.

Too much body fat (especially around the middle) can make your body resistant to insulin, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Your body then makes more insulin. But over time it can’t keep up with the demand. The extra blood sugar then builds up in your bloodstream. This leads to prediabetes. Exercise has the opposite effect of too much fat. It helps the insulin in your body work as it should.

People with prediabetes often have no symptoms. The only way to know if you have prediabetes or diabetes is to have a blood test. Talk with your healthcare provider if you think you need a test for this condition.

Anyone age 35 or older should be tested for diabetes. Because your risk rises as you get older, talk with your healthcare provider about testing if you are 35 or older. If you are younger than 35, you should be tested if you are overweight and at least one of these describes you:

• A family history of diabetes
• Low HDL cholesterol levels and high triglyceride levels
• High blood pressure
• A history of diabetes during pregnancy or a baby born weighing more than 9 pounds
• A member of a minority group that includes African American, American Indian, Alaska Native, Hispanic American, or Asian American/Pacific Islander

If you have been diagnosed with prediabetes, you may need a second test in 1 year to confirm the diagnosis.